The last Crosti about to be inflicted on Wellingborough. This fine portrait of 92029 , last of the Franco Crosti versions of the 9F's , shows clearly the many modifications to the original standard design , with the handrail alongside the front chimney and a footstep on the smokebox side provided for the shedstaff to use when sealing off the front chimney following lighting up as that chimney was bypased once the engine was in action . The main running chimney , which was responsible for the ingress of smoke and steam into the cab is in its original condition in this view , not yet having been covered by the deflector which was later added in an effort to combat that problem , whilst the front of the preheater through which exhaust gases were diverted , can be seen beneath the main boiler and between the main frames. Beginning with 92026 the ten versions were converted to the more conventional design from September of 1959 , a programme which took three years to complete.