The design of the 61xx was developed in detail from the 51xx class (represented at Didcot by No. 4144), with boilers of higher-tensile nickel steel to permit a greater steam pressure. The entire class of seventy engines was built between 1931 and 1935, and all were allocated to work accelerated suburban services.
Here they stayed until 1955, when some were transferred to outlying branch lines and to banking duties through the Severn Tunnel. All passed into BR ownership, but withdrawals began in 1958 as diesel multiple units displaced them.
6106 was built at Swindon in May 1931, and withdrawn from Oxford depot in 1967. She was purchased in working order by a Society member, being sent to the small depot temporarily established by the Society in the old Taplow goods shed. There she was steamed on high days and holidays until able to come to Didcot in October 1967.
At Didcot she has been in almost continual use, apart from repair periods on expiry of each ten-year boiler certificate. Having also worked on certain preserved railways, she has been withdrawn from active service for yet another ten-year major overhaul. She featured in several films including 'The Bliss of Mrs Blossom' when, painted in psychedelic colours, she operated in a contrived snowstorm at Taplow, to the consternation of surprised main-line drivers!