I'd like to add some additional information for you.
The BDV & BDVT ( Break Down Vans, and Tenders) didn't have Diagram numbers, they came under the Pilot Van group.
The OOC Pilot Vehicle was both an BDV & Tender combined and numbered 130 and here's the following data for it.
Length 62ft 0in, width 8ft 0in, Height &ft 2in. W/B 54ft 6in wheels 8x 3ft 7½in.
The following information was by John Lewis In the copy of the Pilot Vans that I'm in the process of updating.
Incand. gas. 9ft volute spring bogies. Gangway officials compartment end (Alteration?). Drop light other end. Cushions in officials compartment. Stove, cupboards & lockers in workmen's compartment. Written " Loco, Carriage & Wagon Dept. Old Oak Common" (on roof board). Area with three windows modified by BR(W) in 1951. Sliding door substituted for two of three window group. Photos: RC2 Fig 427 (bogie). RCA2 Figs 442, 455. As modified RCA2 Figs 457, 458. RWA Fig 315. GWR Sheds in Camera Pl 191. When cond. to R&S Hayes, Bridgend
Dave