At the beginning of the 20th century the station had platforms on all four lines of the West Coast Main Line out of Euston, but with the construction of the Watford DC line the local service took over the slow main line platforms, the slow (semi-fast) main line services were diverted through what had been the fast main line platforms and the fast main lines were moved southward.
The slow (previously fast) main line platforms were almost entirely demolished during the electrification of the West Coast Main Line, with the last platform building disappearing in the 1980s when the LNWR platform canopies were removed. The current footbridge and street-level buildings are not so much the result of modernisation but of three or four major fires which have occurred here since the early 1970s.
The station is occasionally used as a reversing point on the London Underground network by out-of-service Bakerloo line trains when they cannot enter the LU platforms at Queens Park station due to planned engineering work or failures, and/or are prevented from reversing in the Up DC line platform there. The fourth rail (bonded to the traction current return rail) continues towards Kilburn High Road to permit these movements, but the carrying of passengers to Kilburn High Road by LU tube trains is not permitted as the platform height is matched to Network Rail trains (platforms on this line north of Queens Park station are positioned at a "transition" height which is higher than that for normal LU platforms and lower than NR platforms). There are also one or two "rusty rail" journeys made by LU trains each day to keep the fourth rail clean for the relatively infrequent unscheduled diverted LU trains. Kilburn High Road appears on non-public internal London Underground (LU) maps and documents for this purpose.[2][3]