Hi Ceeoh,
I don't know if this is of any help, - but I found this on the 'History of the Metropolitan Police' Site:
'Records for the railway police of the various railway companies do not appear to be amongst the railway staff records held at the Public Record Office, but information about the numbers and organisation of railway police circa 1900 can be found in RAIL 527/1036. The occasional references to 'Police Department' in the railway staff records relate to signalmen, etc'.
Romilly.