When the rebuilding programme (see below) was halted in 1961, further modifications were made to the unrebuilt locomotives. The most notable was on No. 34064 "Fighter Command", which was fitted with a Giesl ejector in 1962 on the grounds that a desired spark arrestor would "suffocate" an ordinary blastpipe. Following some adjustment, the ejector improved smoke deflection and fuel consumption, allowing it to steam well with low-grade coal. As a consequence of the positive experience with No. 34064, preserved No. 34092 "City of Wells" was similarly fitted in the mid-1980s.