The Clerestory sets for MR, GNR and GWR (1899 - 1936) have a speed limit of 130km/h, while the previous 6-wheel set (1887 - 1923) has a speed limit of 135km/h.
Although most locomotives in this era have a limit of 125-130km/h, there are a pair that come out at 1922, LNER A1, SR N15 that exceed 130km/h
The next set that comes out, GWR express set (1923 - 1953) and LNER teak express set (1923 - 1960) has a top speed of 160km/h and 175km/h
I think it would be a smoother transition if the Clerestory set was given 145km/h top speed.
Sounds sensible to me. I'll modify it when I get chance (which may not be for some time unfortunately)
I've made this modification for the next release of the Experimental version of Pak128.Britain - than you for the suggestion!