This is the hint.
On Wednesday 27th September 1939, barely weeks since Neville Chamberlain declared war on Germany, H.A. Taylor (below) wrote to The Times warning of the dangers of cryptic messages being conveyed to the enemy via devices like national crosswords! Barely five months on, the appearance of this crossword in The Times on February 2nd 1940, with the Thunderer’s unique habit of not naming the author of their crossword, (and I very much doubt to this day, that they have the foggiest idea of who it was!), I equally doubt that if No 10 or the Ministry of Defence had got wind, it would ever have seen the light of day! Particularly poignant for me, is that I spent nigh on twenty seven years living in Hither Green between 1981 and 2008, which any residents there will confirm, was during the War the principal rail link to the South and South East of England housing as it did railway marshalling yards and sidings, so vital to the War effort, but suffering massive damage from German bombs. Granted that this crossword appeared in early February, long before the Blitz which in the good authority of my Times Atlas of the Second World War began on the 7th of September of that year, but preparation and precision, rather like their remarkable achievements on the football field, were not lacking in our German opposition, and as in H.A. Taylor’s prediction with the lessons of World War One, we invariably had to play catch-up all the way to the penalty shootout!
Very sorry if I’m offending anybody by my strictly neutral observation some 80 years later, but I cannot help detecting what seems to me, (with the two central solutions in a very strange grid, resembling a couple of railway lines) to be a blatant central message to the Luftwaffe in this puzzle, which uncoded I read: Hello, contact (1 and 4 ac Sod the pass, a wager on the team – DEFILE, SIDE BET) relay please to (2 dn FOREIGN STATIONS – Goering) secondary option (4 dn They don’t immediately come to mind (6,8) SECOND THOUGHTS), after you’ve dropped most of your load on London, on your return drop the remainder on Hither Green (8 dn Sidelines (7,7) RAILWAY SIDINGS) agent confirmed operational (5 dn He knows all the ins and outs of the business (last word referring to Times staff, possibly called away on codebreaking duties themselves!) – DOORMAN signing out (6 dn BUSINESS AS USUAL) 22 ac Among the wellrun second the limits of a yawn are very restricted (4,4,2,5) (Precision bombing required with secondary target) FROM HAND TO MOUTH (my hand to your mouth) and finally 17 dn TRIUMPH an impostor from Kipling, no less!). Clearly, Doorman thinks so, and possibly with good reason! Am I being fanciful? Judge for yourselves! – DA