RAF B-17E Flying Fortresses

I’m hoping somebody here can help me with a fairly obscure detail about RAF Coastal Command B-17s?

In the photo of Alley-Oop you can see the “standard” factory-applied data block . . . US ARMY – MODEL B-17E, AIR CORPS SERIAL NO. 41-9216, CREW WEIGHT 1200 LBS and so on.

I’m trying to find out what this was replaced with – or supplemented with – on B-17Es in RAF service? This Imperial War Museum photo of FL 462, (originally 41-9239 I believe), clearly shows the data stencilling is there, but it’s unreadable. Most of it seems to pretty much match the AAF data, but the aircraft serial number line is much longer. What’s been changed or added? A Lend Lease contract number? I’d guess the format would be standard and apply to B-24 Liberators as well.

Any help will be very welcome.