Apologies if this has been done before but just wondered why there was never a standard approach to the size, style or even presence of smoke deflectors? Given that the size shape and tragectory of loco boilers on all engines capable of running at speed will all impart a similar effect in drawing exhaust back towards the surface due to the lower air pressure I am surprised that the size and design did not also standardise across the regions over time. The lack of smoke deflectors perhaps more than anything gave GWR locos a unique "family" style that makes me wonder whether GWR independence and GWR marketing overruled GWR engineers in choosing to do without them entirely but their absence did not lead to any greater incidence of driver sighting errors. Even within a region we see LNER A1s and A2s carrying large style deflectors whilst the A3s carried an almost cosmetic German style or none at all. Personally I like them, having grown up with Bulleid's giant eared engines, and on the Southern, predecessors like the King Arthurs and Nelsons had half sized deflectors, suggesting that driver experience suggested larger models were required - in direct contrast to GWR practice. They can't all be right!