His paintings are rich with musical and poetic references influenced by "Greek mythology, orphic mysteries and fantasies of Asia, where we are led by Gustave Moreau" remarked Louis Vauxcelles.

His 1915 portrait of a Spanish countess, naked but for a white mantilla, seated between two fully clothed companions (La Maja Marquesa), was publicly denounced and had to be retitled.

Such was his fame that in 1926 Martha Graham[7] titled a dance at her first public performance in New York "Portrait – Beltrán Masses"; in 1929 the temporary removal from a London exhibition of two particularly explicit paintings led to denunciations of censorship but insured an attendance of over 17,000 paying visitors in just three weeks.

Beltrán Masses' portrait subjects included kings and princes, Hollywood stars, and leaders of high society on both sides of the Atlantic, while he was particularly sought out by women who had unashamedly rejected convention and whose lives had sometimes scandalised the public.

Here, the coarse Catalan peasants of his youthful canvases gave way to dark eyed gitanas and recumbent majas, wearing costumes that emphasised their feminine and seductive qualities.

His work as a portraitist became an important source of revenue; European royalty, members of the Spanish, French, Italian and British aristocracy, the wives and lovers of newly rich entrepreneurs and leading actors and dancers all vied for his attention.

His work bears superficial comparison with that of his friend Kees van Dongen, who, like Beltrán, captured the escapism that characterised post-First World War society.

His famous ‘beltran blue’ casts the city in a romantic perpetual evening in many paintings, their mysterious figures often only party lit while dark shadows exaggerate their features or costumes.

The poet, novelist and critic Camille Mauclair (1872–1945), an advocate for the symbolist movement of the late nineteenth and early twentieth centuries also praised Beltrán Masses.

Arsène Alexandre later wrote the introduction to Beltrán’s illustrations for a 1929 edition of Il Trionfo della Morte (1894) by the renowned Italian poet Gabriele d’Annunzio[8] at the Galerie Javal and Bourdeaux.

The favourable reviews Beltrán received in America and the praise for the “psychological” insights that he captured brought him a succession of commissions from American East and West Coast society.

Beltrán Masses' later connections with French Cinema were cemented by the inclusion of twelve paintings and three drawings in the 1934 film, Le Rosaire, staged by Gaston Ravel and Tony Lekain.

When ill-health and failing eyesight, which began deteriorating in the mid-1930s, required urgent attention Beltrán and another followed in Madrid, but the painter returned to Paris the following year hoping to resume his career.

The recent revival of interest in Beltrán Masses owes much to the care with which his heirs retained not only the paintings they had inherited but an extensive archive, which includes many photographs from the 1920s and 1930s as well as exhibition catalogues, reviews and mementoes.