 In 1947, he was one of the founders of the Birmingham Artists Committee and in 1961 he organised the "Four Letter Art" exhibition at the Royal Birmingham Society of Artists, having been elected a member the year before.Although there was no organisational link, Denning's work exhibiting contemporary art in the city was acknowledged as an influence by the artists who founded the Ikon Gallery in 1964, and he held a solo exhibition at the gallery two years later.Denning was also a published expert on Spanish playing cards.