

Sorry for having been one of the 'big list' folks in the past. To compress it down and answer your question of "One thing to fill in a niche", I'd still be thinking in terms of a 4-coupled express engine as an alternative to the current Singles.
This is on the basis that they generally had more varied careers then the Singles, shifting more naturally to branch line or light duty usage then the larger 4-2-2s. For example, the LNWR's Precedents shifted from WCML expresses to cross-country locals, whilst the Midland Kirtley 156's similarly morphed from crack express locos to station pilots and branch engines in their almost 80 year career!
I acknowledge the difficulty in finding reliable power output stats for machines of the period. Unfortunately, I'm currently moving home so all my railway books are in storage boxes, otherwise I'd try to offer more information.
Just my personal tuppence worth! Thanks again
