I think that clears it up nicely. Certainly there's not much evidence for a black number patch either, so it's looking like a vacuum braked 1/109 that also may not have had the full vacuum kit either.
Great to see these oddities on film, thank you.
I'd be keen on reading the MB articles if possible.
Cheers
Tony
These are the MB articles. by far the most accurate on BR minerals
Fidczuk, Peter. (1991a) The 16ton steel mineral wagon, part one Prewar and wartime designs.
Modellers Backtrack vol. 1 (part 3) pp 124 - 133.
Drawings - official of the slope sided mineral, Hurst Nelson 14/16t private owner (435), ex MWT/SNCF diag. 1/112 (119).
Fidczuk, Peter. (1991b) The 16ton steel mineral wagon, part two Later Pre-Nationalisation developments.
Modellers Backtrack vol. 1 (part 4) pp 148 - 156.
Drawings - LNER diag. 188/BR diag. 1/103 ex MOT rivet (439); BR diag. 1/105 ex MOT rivet (418); BR diag. 1/102 ex WD welded (123).
Fidczuk, Peter. (1991c) The 16ton steel mineral wagon, part 3: Developments under British Railways.
Modellers Backtrack vol. 1 (part 5) pp 220 - 230.
Drawings - BR diag. 1/108 welded (116); BR diag. 1/109 riveted (117); BR diag. 1/108 rebody welded.
Paul