Fairbairn-Sykes Dagger ( Fighting Knife ) 1st Pattern

Diagram of Fairbairn-Sykes Fighting Knife, issued to British Commando forces in WWII. Image taken from page 69 of Fleet Marine Force Reference Publication 12-80, Kill or Get Killed by Rex Applegate (who worked with Fairbairn).



Length 11.5 inches (29 cm)
Blade length 7 inches (18 cm)

Sources:
en.wikipedia.org/wiki/Fairbairn_Sykes
en.wikipedia.org/wiki/William_E._Fairbairn
en.wikipedia.org/wiki/Fairbairn%E2%80%93Sykes_fighting_knife
www.fairbairnsykesfightingknives.com/examples.html