No to mention their monopoly on the Canterbury & Whitstable, of course ............. I've always wondered what the thinking was behind building them with 5' wheels : as such they should have been quite capable mixed traffic branchline machines - especially with the 'H' boiler ........ maybe the 'front end' was too restricted ?
Not entirely. Stirling O class were used with short chimneys on the line for a while (long before BR days though). And yes, both O and R classes had the same chassis and boiler (even when converted to R1 and O1 respectively).