This 'Outlines of Power' article was the first in a series of centre-spread features by Mike Turner that the magazine 'Rail Enthusiast' ran during the early 1980s.
It depicted some of BRs more interesting diesel and electric locomotives and began, naturally enough, with the Deltics.
The annotations in the picture may be too small to read here so I have reproduced them below:
"Deltic" Prototype built 1955 by English Electric. Powered by two Napier "Deltic" 18-cylinder, 1,650 bhp engines, total 3,300 bhp. Weight: 106 tons. Maximum tractive effort: 60,000lb. Notes: Now at the Science Museum, Kensington.
First Production "Deltic" in service, D9001 St Paddy. Power details as above, but weight 103 tons and maximum tractive effort 50,000ib. Built at Vulcan Foundry, Newton-le-Willows. Notes: One of the first two "Deltics" to be withdrawn, and now broken up.