Moving back to the Deltics discussion, the ECML also had a selection of 47s and in the air-con era 47/4s which operated alongside the 55s. Was there are particular pattern as to which route or services were specifically rostered Deltics and what sort of split was there?
Presumably all the best/named services had a Deltic?
There were two distinct eras - pre 1978 and 1978-81 : essentially before and after the Deltics were replaced on the premier services by HST.
IIRC
Before HST, I believe there were more distinct diagrams for Deltics and 47s to take into consideration the 5mph difference in top speed etc.. So for example I think you could get a London to Newcastle train / or a London to Leeds train on a Deltic timing and another one later in the day on a 47 timing. Generally speaking the more prestige trains were Deltics.
In practice the non-availabilty of a Deltic on a Deltic diagram could often lead to a 47 replacement.
After HST, the Deltics were relegated mainly to the York and Hull semi-fast trains. These were timed for Deltics. The most common pattern was for the HST to leave Kings Cross at XX:00 and then the Deltic semi fast at XX:05. The Deltic had to make it to York stopping at all the stations Huntingdon, Peterborough, Grantham etc before the next HST - so the timings were quite tight. When the 47s finally replaced the Deltics in 1981 on these services the timings were relaxed.
Again, in practice the non-availabilty of a Deltic on a Deltic diagram could often lead to a 47 replacement.
Dictionary defintion of despair - It is 1980, you have cycled to a bridge on the ECML, it is a lovely sunny day, you have your camera ready, the 12:05 Kings Cross to Hull is due any minute, the tension is building and then suddenly you see a flat yellow front approaching in the distance.
I have been there, felt that.