I don't know if this will help you, but I wrote to Metropolitan Police Historic Collection
Unit 7
Meridian Trading Estate
Bugsby Way
Charlton
London
SE7 7SJ
e-mail historicstore@met.police.uk

It took about 4 months to get an answer back, but I did get what I wanted for my family, give them all the details that you can possibly find, I'm sure you will win.
Your relatives probably new mine, as they were at Bow

Hope this will help,. Good luck.