Recommended reading
CB Collett A Competent Successor by JE Chacksfield (Oakwood Press) The 0‑6‑2 Tank Papers Nos. 1 & 2 by Ian
Sixsmith (Irwell Press)
The Locomotives of the Great Western Railway Part 5 (RCTS)
Collett & Hawksworth Locomotive by Brian Haresnape (Ian Allan)