Betjeman Again: 'a whim of iron'

Watching last night's BBC4 documentary Return to Betjemanland, I was struck by a phrase used by Antony Powell to describe Betjeman: he had, said Powell, 'a whim of iron'. It's just the phrase to describe the mix of cuddly insouciance and steely purpose in Betjeman's personality - and, by extension, the tension in his verse between whimsy and something very much darker. No doubt Powell thought of the phrase himself, but it seems it was in circulation, having been attributed to Oliver Herford, 'the American Oscar Wilde', who is supposed to have said that his wife 'has a whim of iron'. Curiously the phrase also crops up in a song by the contemporary American folk singer Slaid Cleaves: 
 'She had a whim of iron.
 You couldn't tell her no.
 And if you did she'd prove you wrong
 And say - I told you so!'
Anyhoo, Return to Betjemanland was a solid job, presented by the ever more parsonical A.N. Wilson in a brown three-piece tweed suit of antiquated cut. He took us on a pleasing tour of the familiar landmarks, aided by dips into the extensive Betjeman TV archive, and it was all very enjoyable. Only towards the end did the tone darken, and Wilson was unflinching in exploring the dark underside of Betjeman's glittering surface - the well earned guilt, the secrets, the self-doubt, the literary and social insecurity, the complicated love life... The very things, I suppose, that put the iron in his whimsy.