If you follow the link,you'll see that it's not exactly Gill Sans. The original poster was hand-lettered in the style of London Underground signage (of which, by the way, Gill Sans is a derivative). So siblings, but not the same.
Also, www.b3ta.com/board/10765797
(,
Mon 31 Dec 2012, 13:06,
archived)
Also, www.b3ta.com/board/10765797