Green’s Dictionary of Slang

Margaret (Rose) n.

also Mary Rose
[rhy. sl.; ult. Margaret Rose or Princess Margaret (1930–2002), the Queen’s sister; the ship Mary Rose, a sunken Tudor warship brought to the surface in 1974 ]

the nose.

[UK]P. Wright Cockney Dialect and Sl. 105: Margaret Rose ‘nose’.
[UK]R. Puxley Fresh Rabbit.