If you check out this website it has up to date info:-
HOME OF THE BAC 1-11 ON THE WEB
It looks like there are only 3 airworthy 1-11s and the one at Boscombe Down is due to retire in July.
As a person who saw the first one fly on his 10th birthday and worked on them for a number of years, it's a shame there won't be one available for the 50th birthday next year at Bournemouth-Hurn.