[David_Hayward (RIP)]

Yes it's a Winch truck!
L 4999775 to 4999845 Contract S/M 2569 'LORRY 3 TON 4 X 4 WINCH ARTICIZED'. There is a photo in the Imperial War Museum of one, # IWM PHOTO KID 1284...

The other truck is in the batch L 5421311 to 5421420 to Contract SM 2654 for 'LORRY 3 TON 4 X 4 STORES'. The census number L 4999868 is actually from the series:
L 4999866 to 4999912 Contract SM 2568 'LORRY 30 CWT. 4 X 4 OFFICE ARTICIZED' E.G. L 4999883 IWM PHOTO KID 4589 but I am sure that the vehicle is actually a C60L. It would appear that the census number is not correct on the face of it.

L4948501 to 4950228 Contract SM 2570 'LORRY 3 TON 4 X 4 GS ARTICIZED' AS AT 1 OCTOBER 1942: 1,728 PRODUCED

I am going to add the serial numbers quoted into my database and then repost all 1942 C60S and C60L models known to compare serial number and dates.