In article , Clive D. W. Feather
writes
The bit of the working timetable for Cruisers that I've been able to
find gives:

KX depart XX15
[...]
Royston pass XX47 2 engineering allowance

and Cambridge at XX61 (IYSWIM) of course.

Feeding that into a spreadsheet, I get the following:

A B C D E
King's Cross
Finsbury Park 43 46 40 3.5 1.5
Alexandra Palace 99 118 84 1.5 1.5
Potters Bar 84 88 81 5.5 4.5
Welwyn Garden City 101 107 96 4.5 4.5
Woolmer Green 106 121 94 2 2
Stevenage 111 127 99 2 1.5
Hitchin 87 95 81 3 2.5
Letchworth 54 59 50 3 2
Royston 88 91 85 7 6
Cambridge 56 57 55 14 8

A = average booked speed between locations
B = booked speed using a time 0.25 minutes less
C = booked speed using a time 0.25 minutes more
D = booked time between locations
E = time between locations required for 100mph

B and C are to allow for the fact that booked timings are only given to
half minutes.

The 2 minutes difference between D and E out of King's Cross is to allow
for the train to accelerate, so we should expect the same at Cambridge.
That leaves 4 minutes lost between Royston and Cambridge in 13 miles.

--
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