Metropolitan Cammell Renumbering?

[euryalus]

I was looking at a photograph of a hybrid dmu 3-car formation, comprising class '121' single unit railcar No.55029, class '101' motor brake second No.54396 and class '101' motor brake second No.51221, but when I looked up these vehicles in a 1960s Ian Allan dmu book I could find no mention of No.54396 - were some class 101 (and class 117?) vehicles re-numbered in the 1980s?

 

[theblackwatch]

All DMUs in the 56xxx series were renumbered into the 54xxx series in 1983/84 when they were added to TOPS. This was to prevent confusion with Class 56 locos. 56396 became 54396. Suimilarly, DMUs numbered 50xxx became 53xxx.

 

[euryalus]

All DMUs in the 56xxx series were renumbered into the 54xxx series in 1983/84 when they were added to TOPS. This was to prevent confusion with Class 56 locos. 56396 became 54396. Suimilarly, DMUs numbered 50xxx became 53xxx.

Thank you for your clear and informative reply - I note that 56396/54396 was in fact a driving trailer composite, and not a "motor brake second" as I suggested earlier!

 

[Genocide]

To add a bit - 50xxx cars were powered, 56xxx were unpowered driving cars.

The anomaly was spotted after all the Deltics had gone so 121/122 single cars retained 55xxx, but to add to the confusion non drive trailers were 59xxx but kept their numbers after the 59's arrived.

I don't recall any number clashes and probably TOPS had been whipped into shape by then, but it was quite possible to be riding in 59xxx on Paddington suburbans and pass 59xxx on aggregates at one point.

 

[455driver]

It was only when DMUs (and coaches) were added to TOPs that it became a problem. Up to that point there wasnt any chance of confusing 55016 (the loco) with 55016 (the DMU) because people used common sense, unfortunately computers dont possess common sense hence the renumbering.