As Hugh S. Roberton died in 1952, his works will be fully public domain in UK terms in another couple of years (70 years post death). However, people have been taking his lyrical adaptations and passing them off as trad. for decades.   As everyone knows from this thread, Roberton's 'Mingulay Boat Song' is an original lyrical work, even if it was set to a trad. tune.. but with about 2 years left of copyright left in it, I don't suppose it will matter too much.. apart from recording the origins for posterity - and his descendants no longer benefitting as they have when credited and put through the copyright agencies.