I could add a myriad of tales about these services as I was a secondman at Kings Cross from 1975 to 1978, and had probably the most enjoyable days of my railway career there. It was very interesting as we had the last of the traditional loco hauled services on the suburban and main lines.
Suburbans were mostly loco hauled in the peaks, with a number of DMU services. All loco hauled suburbans were class 31 by then, usually with 6 cars. Cambridge fasts and semi-fasts were usually Mk1 main line stock,again with 31s, but rarely a 47. Suburban stock was booked to work to Cambridge and Peterborough, as well as places in between.
Early turns would typically book on at about 0400 to 0600, with crews going pass to Finsbury Park to prepare the locos, then light engine to one of the many outstations where the stock was berthed, typically Hertford North, Welwyn, Hitchin or the local sidings at Finsbury Park and Caledonian Road. Late turns would start at about 1500, with a peak hour journey from FP to Moorgate, a trip to the outer limits, berth the stock, then light engine back to Finsbury Park.
The locos would be booked to arrive about an hour before departure to steam heat the stock. This was a problem for me in the early days as I hadn't been trained on the steam heat boilers! Up trains would work to either Kings Cross or Moorgate. The few Broad street services were worked by the Rolls Royce engined DMUs. some of the Cravens units would work through to Moorgate. The Metro Cam units would not normally work the widened lines as they weren't fitted with trip cocks to work on the LT section.
On the Cambridge buffet trains, we'd usually try to achieve 100mph on the "up" run, on the long down hill stretch through Wood Green tunnel, where we once had 102 out of a 31 with a buffet set! On the down line in summer, the locos would often overheat approaching Potters Bar. This would only happen with the radiator at the leading end, as the air flow missed the radiator grilles! As soon as power was eased off past Potters Bar, the system would cool down again!
My regular driver in 3 link at the time was a Yorkshireman called Ron Birch. His son followed him into the footplate grade. Later when I progressed to 2 link where we usually worked to Leeds, I was with Ron "Brusher" Warren who lived at Hatfield. He used to boast that his runner beans used to grow up N2 boiler tubes that he "rescued" from his days at Hatfield loco!
My view at the time was how uneconomic the whole operation was, with over 300 drivers and some 200 secondmen at Kings Cross alone. This of course changed dramatically with electrification.