Sorry, it's not RAF memorabilia but a football one. It refers to a football chant:
There Were Ten German Bombers In The Air,
There Were Ten German Bombers In The Air,
There Were Ten German Bombers, Ten German Bombers,
Ten German Bombers In The Air.
And The RAF From England Shot One Down.
And The RAF From England Shot One Down.
And The RAF From England,
The RAF From England,
The RAF From England Shot One Down.
There Were Nine German Bombers In The Air… etc
http://nmallory.exit-23.net/tag/World+Cup
