Green’s Dictionary of Slang

lion’s lair n.

also lion’s share
[rhy. sl.]

a chair.

[UK]J. Franklyn Dict. of Rhy. Sl.
[UK]J. Jones Rhy. Cockney Sl.
[UK]P. Wright Cockney Dialect and Sl. 103: lion’s lair ‘chair’.
[UK]R. Puxley Cockney Rabbit.