The fast lines at Peterborough were put in after years were most up freight had to use Peterborough North's platform two with it's 20mph speed limt (The 'North' has now been removed from the Peterborough's station's name ).
Trains stopped at Peterborough station longer in steam days, with mail to load and unload on most trains. Steam engines took water and were often changed at Peterborough. Vans of mail were added by the N2 station pilot. All this soon blocked the up road with many coal trains to London causing long tail backs of freight and even passenger trains waiting to get though Peterborough station.Platform 2 had a dog leg that the LNER planed to remove. Crescent bridge was built with this in mind. The 2nd World war and then nationalization put all this on hold. It was not till the late 1960s after steam had gone that a start was made. The dog leg was removed from platform 2, platform 6 was done away with, and a new up and down though tracks were put in and a new island platform 4 and 5 put in to the west of the two new tracks.
Though trains can save a lot of time with a 105mph speed limit on the fast lines as against the 25mph that was though the station.
A class 47 on a down train at Peterborough on the down fast.
High Speed Train (HST) power car 254008 on the down fast at Peterborough station
Note the space were in 2014 platform 3 was put in on the up fast
Page updated 17/11/2018