There is a description in Brian Webb's book 'British Internal Combstion
Locomotive 1894-1940' publ David & Charles.
Looked pretty like a 2-6-2 tank but had a horiz. opposed 8 cylinder engine
mounted transversely. You are right, steam first to inner ends of cylinders
diesel on outer, but both could be used simultaneously. Steam initially from
oil fired boiler, but when up & running steam generated in boiler by waste
heat from diesel.
Completed in 1927 & tested with reasonable success on main line running.
Reliable apparently, but piddling around with such a novel device during the
depression contributed to the closure of the old-established Leeds firm.
Art Walker
