Hrothgar:
Extended by the copyright act 1988, see Here

Quote from above link:
"Duration of copyright
For literary, dramatic, musical or artistic works; 70 years from the end of the calendar year in which the last remaining author of the work dies, or the work is made available to the public, (by authorised performance, broadcast, exhibition, etc.)
Sound Recordings and broadcasts; 50 years from the end of the calendar year in which the last remaining author of the work dies, or the work is made available to the public, (by authorised release, performance, broadcast, etc.)
Films; 70 years from the end of the calendar year in which the last principal director, author or composer dies, or the work is made available to the public, (by authorised performance, broadcast, exhibition, etc.)"

CHEERS

Nigel