Austin Towing Vehicle ex NFS. Later type with Shrapnel roof panels. Slit in roof was for the hand operated bell strap.
Labels are the inventory card, show what was carried in each locker. These cards are Post war and as the labels state for Southend on Sea Fire Brigade. This looks like it was used by them as a salvage tender, from what i can see listed on the cards.
As it does not appear to have the cutouts on each side that would indicate a convertion to a hose real tender with 2 tanks fitted under the crew seats and a hose real and pump, or the 3 way valve and hose copling on the side. This was a common practice where these vehicles when past over from the NFS to local brigades.