Question: What specific institution did Barnes indicate could not be a rival of the Royal Institute?
Sentence: Soon after the passing of the 1931 Act, in the book published on the occasion of the Institute's centenary celebration in 1934, Harry Barnes, FRIBA, Chairman of the Registration Committee, mentioned that ARCUK could not be a rival of any architectural association, least of all the RIBA, given the way ARCUK was constituted.
Answer in sentence: yes