Gerontius, and a Jarring Phrase

A while back, having read a devastating German and a sour Austrian novel back to back, I vowed to return to English fiction with my next selection from the charity shop fiction shelves. Those trusty shelves duly obliged by delivering into my hands Gerontius by James Hamilton-Paterson, a novel that I remembered having intended to read when it came out (in 1989 – 35 years ago now!).  
  Gerontius is a beautifully written, psychologically convincing account of a sea voyage undertaken in 1923 by an ageing Sir Edward Elgar, taking him over the ocean to Brazil and on into Amazonia as far as Manaus. He is known to have visited and admired the grand opera house there, but otherwise the whole unlikely episode is barely documented, so Hamilton-Paterson has free rein to make of it what he will. So far, I am only about halfway through – it's a fat book and I'm a slow reader – but I am impressed and thoroughly engrossed. As well as being an account of a sea voyage, Gerontius is also a journey around Elgar's life and mind, his anxieties and preoccupations, his uneasy relationship with his muse and with the social world, his grief for his wife, his many exasperations, his love of tinkering and 'japes', his susceptibility, perhaps, to something like late-life romance... I've read nothing else by this author – described on Wikipedia as 'the most reclusive of British literary exiles' – but I'm strongly tempted by a novel titled Cooking with Fernet Branca., which sounds very different indeed from Gerontius. 
  Anyway, to the point, if it is a point. There I was, reading away in Gerontius, when I was snagged by a jarring phrase that struck me as surely an anachronism. A character uses the expression 'economical with the truth', which I don't recall ever having heard before it entered the mainstream in 1986 after a senior civil servant (Sir Robert Armstrong) used it in the 'Spycatcher' trial. Surely no one in 1923 would be using the phrase? The idea itself, but not the wording, can be found in Mark Twain – 'Truth is the most valuable thing we have. Let us economise it' (1897) –  and Edmund Burke: 'As in the exercise of all the virtues, there is an economy of truth' (1796). It seems the actual words 'economical with the truth' might well have been in circulation, but are only recorded in obscure sources – The Iron and Metal Trades: Birmingham, 1897 ('One can say without being economical with the truth that they are in a state of "masterly inactivity"'), The Weekly Underwriter, 1897 ('The insurance superintendent of Kansas is said to be very economical with the truth'), and the record of debates in the New Zealand House of Representatives, 1923 ('It is not well to be too economical with the truth'). So the use of the expression in Gerontius is perhaps not anachronistic; it just sounds that way. Not that it matters.