Masses of individual scores and arrangements on this site here: 304 items on 26 pages.
http://www.prestoclassical.co.uk/sm/composer|10034-b/9
(Sorry, iPad refusing to do blickies!)

According to Wikipedia, Roberton did found the Glasgow Orpheus Choir and disbanded in 1951 when he retired. It also says that the choir was banned from broadcasting by the BBC during WW 2 as he was an affirmed pacifist.