In September, during a trip to Provence, he discovers the Cistercian abbey of Montmajour. The Romanesque buildings impress him and give rise to a major series of watercolours and paintings. The Municipal Museum of The Hague acquires the painting Invention de l’homme.
Inspired by studies of Alla Goldschmidt that he had previously made, he paints La religieuse which was acquired by the Goldscmidt and then bequeathed by the model to the Royal Museums of Fine Arts.
Michel Seuphor references Gaston Bertrand in his Dictionnaire de la peinture abstraite (Abstract painting dictionnary), published in Paris.

In January, he exhibits his work for the second time at the Stable Gallery in New York. The Belgian art critic Paul Caso writes that “[Gaston Bertrand] appears as being the most prominent Belgian non-figurative artist”. Due to some bargaining undertaken by the organizers and part of his colleagues, Gaston Bertrand refuses to take part in the Belgian art exhibition (non-figurative artists section) held in the context of the Brussels International Exhibition.

The artist Jo Delahaut devotes an article to Gaston Bertrand in the Parisian magazine Aujourd’hui.
After many preparatory studies, Betrand eventually completes the order made by the Namur Bishopric under the initiative of Canon Lanotte: during the summer, he paints two frescos on fresh mortar (Sainte Julienne de Cornillon and La Trinité) in the Sainte-Julienne Church of Salzinnes, not far from Namur.
During the months of October and November, he goes on a second trip to Spain. He goes through Saint-Jean-de-Luz where he draws the port, and then visits the Altamira’s prehistoric caves which inspire him a significant number of drawings and watercolours.
Finally, goes to Madrid and Toledo where he paints watercolours. At the Prado, some Iberian Romanesque frescos inspire him for the creation of unexpected images (Le prophète, L’offrant, L’ange fabuleux).

He is invited to participate in an international exhibition held at the Solomon Guggenheim Museum of New York. The eponymous foundation awards national prizes to the Belgian artists Landuyt, Delvaux, Van Lint, Burssens and Bertrand, who receives the prize for Printemps gris.
He starts his first researches on the theme of the effigy of Pius XII.

First watercolours on the theme of the Paris subway.
During the summer, Bertrand has several sitting sessions with his friend, the lawyer Marcel La Haye. From the studies drawn during these sessions, he creates over the years, and using diverse techniques, a multitude of works representing the theme of L’homme au jabot (man with a crop).
He paints Florence Médicis (Ghent Museum) and Chapelle des Médicis (Gaston Bertrand Foundation).

The filmmaker Jean Antoine devotes a short film to the artist with funding from the Radio-Télévision Belge (Belgian Radio and Television).
Gaston Bertrand receives the Talens award.
On the occasion of his second exhibition at the gallery La Roue, he stays in Paris and, as he also did the following year, captures the perspective of some streets in the Latin Quarter, which gave rise to a series of watercolours.
He is appointed Knight in the Order of the Crown.
In September, he stays in Moustiers-Sainte-Marie (Provence, France), where he produces twenty-five large pen and ink drawings of the landscapes.
On 25 December, he moves with Betty in the house-studio that they have bought in Paris.
He devotes forty large ink and brush drawings and twenty-seven small pen and ink drawings to the theme of Altamira.

Stay in Paris during which the artist particularly focuses on the Odeon district: ten bamboo brush drawings later give rise to around ten watercolours and as many oil paintings.
Two Brazilian galleries show the works of the artist in São Paulo and Rio de Janeiro.
During the autumn, Gaston and Betty have a two weeks stay on the island of Comacina (Lake Como). The perspective of the narrow streets of the city of Comacina inspires a dozen watercolours.

Gaston Bertrand is asked to create a large decorative panel for one of the restaurant halls of the Royal Institute of Artistic Heritage in Brussels.

He produces, from views of the Alpes-Maritimes, twenty-four ink drawings that he transposes on Chinese silks with coloured inks.
Michel Seuphor and the art critic Jan Walvarens devote several columns to the artist in the book La peinture abstraite en Flandre, directed by Michel Seuphor.

During a new stay in Paris, Bertrand draws fifty-two sketches in the subway which are the basis for as many watercolours, as well as around thirty drawings and twenty paintings.
In Saint-Martin-Vésubie and Venanson, he makes twenty pen and lead pencil drawings as well as eighteen watercolours, from which he produces twenty-six oil paintings.
He produces twenty-four paintings, including Pour un mur and D’abord la forme.

At the invitation of his friend, the lawyer Marcel La Haye, Gaston Bertrand gives a conference on painting held in Brussels on 1 April and attended by the Amis de l’Université de Louvain (Friends of the University of Louvain).
Long stay in his Parisian studio (from 7 April to 14 May).
In September, he goes back to Venanson where he produces the series of ten large drawings entitled Tous les chemin, all of which gave rise to paintings.
He donates 158 drawings to the Royal Museums of Fine Arts of Brussels.
Second personal exhibition in New York, at the Catherine Viviano Gallery.
Among the sixteen paintings he produces that year, there are eight large format, including Montmajour I and II.

From the end of May to 21 June, Gaston Bertrand stays in Venice for the 33rd Biennial. He is invited to exhibit around fifty watercolours and oil paintings in the Belgian Pavilion (introduction to the catalogue written by Philippe d’Arschot).
As he discovers the City of the Doges, the Saint Mark’s Basilica and Square provide him the inspiration for a series of large temperas.
In October, he takes back the lead of the painting workshop of Saint-Luc but assigns the daily animation of the workshop to his former student Camille De Taeye. He definitively leaves the school in 1969.
In November, La Roue and Le Damier, the two Parisian galleries promoting the work of the artist, simultaneously show his works. This is the opportunity for him to stay in Paris from 9 November to 19 December.
He produces a series of thirty-one watercolours inspired by the subway.

He stays in La Panne, on the Belgian coast, during the month of May. The sketches of the beach covered with parasols give rise to a series of thirteen large watercolours and temperas in 1978.
A tribute exhibition is organized for him by the group Hainaut 5 at the Museum of Fine Arts of Mons.

The French State acquire the large painting Odéon (97 x 146 cm) for the collections of the National Contemporary Art Fund in Paris.
During the spring, he stays in Paris and repeats the experience of 1964 in the Paris subway: he draws twenty-seven sketches which constitute the basis for watercolours.
From 9 August to 3 September, he stays again in Paris.

He becomes a member of the Belgian Royal Academy.
In September, he goes to the Belgian Ardennes and stays in Louette-Saint-Denis. The paths of the neighbouring villages give him the inspiration for eighteen Indian ink large drawings.

Two stays in Paris (in March and September).
Stay in Saint-Martin-Vésubie where the artist produces eighteen lead pencil and red chalk drawings.
He makes six dry point engravings, including Dieu le Père, Grand personnage et Religieuse. 
Richard Foncke publishes a new monograph in Ghent, written by the art critic Jacques Meuris.
Karel Geirlandt publishes the article “Gaston Bertrand ou les théorèmes de la sensibilité” (“Gaston Bertrand or the theorems of sensitiveness”) in the magazine Art International.

Two stays in Paris (May-June and August).
In September, last stay in Saint-Martin-Vésubie and Venanson where the artist makes a photographic report.

He goes on holidays to Brûly-de-Pesche, not far from Couvin (July) and to Gembes-Mont, close to Gedinne (September).
At the request of the Ministry of culture, the publishing house Editions Irène Dossche produces an important monograph devoted to the artist and written by Francine-Claire Legrand, who was then curator of the Modern Art section of the Royal Museums of Fine Arts in Brussels.
Gaston Bertrand is appointed High Officer in the Order of the Crown and Knight of the Order of Léopold.
He creates seven dry points, including Le double visage and Sa Sainteté Pie XII.

From 7 January to 4 March, he travels by plane to Andalusia. The village of Mijas inspires him twenty-one drawings which then gave rise to a significant series of watercolours. He also visits Granada.
Two stays in his Parisian studio (from 5 March to 8 April and from 17 June to 6 August).
He paints, among other works, two large compositions: La chose essentielle and Sur des accents brun vert et bleu.
He makes a short stay in Knokke during the month of December.

He travels again to Andalusia from 5 January to 4 March. Several drawings produced in Marbella give rise to watercolours. He also visits Ronda.
Stay in Paris (July-August).

The Royal Museums of Fine Arts of Belgium organize a retrospective exhibition of Bertrand’s works: “the first milestone of a task that must be fulfilled, that of paying tribute to the Belgian artists who have created a work that goes beyond our boundaries”, as underlined by Philippe Roberts-Jones in the introduction to the catalogue.

Serge Goyens de Heusch simultaneously presents an exhibition of the artist’s recent works at the Armorial gallery.
Bertrand paints three commissioned portraits.

Following the retrospective held in Brussels, an exhibition devoted to Gaston Bertrand is also under preparation at the City of Paris Museum of Modern Art, which was at that time directed by Jacques Lassaigne. Unfortunately, the project, although well advanced, is halted due to the curator’s departure.

From 28 January to 22 March, Bertrand travels again to Andalusia where he stays for a long period in Marbella and also visits Malaga.
In August, Gaston Bertrand must undergo a surgical operation and is hospitalized.
In October-November, an exhibition showing the portraits painted by the artist is held at the Dhont-Dhaenens Museum in Deurle. That same exhibition was shown, two years later, at the Paul Ide Gallery in Brussels.

From 31 January to 13 March, holidays in Palma de Mallorca in the Balearic Islands.
In May, stay in the Parisian studio.
Wishing to protect his work, Gaston Bertrand contacts the Ministry of French culture (now the equivalent of the French community ministry of culture) with the hope that, with the donation of his works and of his properties after his death, a small museum could be created in his house on Aubépine Avenue. Unfortunately, these repeated contacts were not be successful.
He paints a series of twenty-seven watercolours on various themes.

Among the sixteen paintings that he made that year, three are painted with acrylic.
On 13 December, Gaston Bertrand formalizes his relationship by getting married with Betty, his life companion.
Jean Guiraud writes the catalogue of the exhibition devoted to Gaston Bertrand’s portraits, which is held at the Paul Ide Gallery in Brussels.

From 2 February to 14 April, third stay in Andalusia, in Nerja; with a visit to Malaga and a four days stay in Antequera.
He produces thirteen tempera watercolours based on sketches drawn in La Panne in 1967.

Two stays in the Parisian studio (in summer and in autumn).
He is appointed High Officer of the Order of Léopold.
Twenty large drawings, for which he used mixed techniques, are devoted to the theme of Saint Mark in Venice.

At the end of March-beginning of April, he produces thirteen sketches in the Paris subway: these are the last studies on that theme and each of the sketches gives rise to a watercolour and to the large painting Lumière dans le souterrain.

The Royal Museums of Fine Arts in Brussels hold a major exhibition showing the drawings donated by the artist (6 June -17 August).
In June, Bertrand goes to Ostend for a personal exhibition: he starts a new series of coloured pencil drawings inspired by the port and the trawlers. That series was completed in 1984 and 1985.
He explores again the theme of self-portrait with eighteen sepia ink drawings. Twenty more drawings are devoted to Betty.
He spends the month of September in Switzerland with his wife. They stay at the Château d’Oex and visit Montreux, Geneva and Rougemont.