http://www.steamcar.net/z-bruin-2.html says
1. Make.............................Stanley
2. Model............................735B
3. Year..............................1919
4. Chassis No:-.................19078
5. Reg No:-.......................DS 8923
6. Engine No:-..................20hp number unknown

https://www.youtube.com/watch?v=NeiyB5zF7rA

Registration number: DS 8923
✗ Untaxed Tax due: 01 May 2008
MOT Exempt
Vehicle make STANLEY 735B
Date of first registration April 1991
Year of manufacture 1919
Cylinder capacity (cc) 2682 cc
CO₂Emissions Not available
Fuel type PETROL (really??)
Export marker Yes
Vehicle status Not taxed
Vehicle colour BLACK