Ex-GWR locos striking their cylinder casings on "foreign" routes was nothing new - Old Oak Common had to deal with this regularly after summer trips down the West London to South Coast resorts. The myriad routes possible through Kent were a particular issue. Exacerbated by the quite mid-range 43xx, a WR go-anywhere type, having the maximum 18.5" cylinder diameter, so as big as anything. The Southern put some effort into clearing routes like Reading-Redhill specifically for them, but odd sidings and especially curved platforms could catch them out.
I certainly remember Taunton stalwart 4932 Hatherton Hall being on shed with scrape marks down the left hand cylinder cover. Nobody would admit when it happened ...
There were other issues as well. When the Royal Train came over Taunton-Barnstaple in the 1950s, preparation was immense. Taunton's like-sounding 43xx twins 6327 and 6372 were sent to Newton Abbot works to be repainted green, but the big spindly viaducts on this route, which saw these locos every day, were banned for double heading. So the train stopped at the approach to each, the first loco was detached and ran across, then the second loco brought the train over. Reattach, on to the next one.