Great ! About time for another Mosquito question !

An actual event which has entered RAF mythology.
On 11th July, 1942 six Mosquitoes of 105 Squadron raided Flensburg. Sgt Rowland, flying BIV DK296 brought back an unusual 'souvenir'.

What was it ?

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"Stand by to pull me out of the seat if I get hit" - Guy Gibson