[EDIT: I seem to have accidentally deleted this twice!]
The bankruptcies section of the 28th Nov. 1972 London Gazette-
https://www.thegazette.co.uk/London/issue/45838/page/14168/data.pdf - includes an Edgar Wilfred Grimstone of South Croydon, publisher. References to the new Lord Grimstone's father (
https://www.thisismoney.co.uk/money/markets/article-2351517/Will-Maggies-mastermind-sell-offs-boss-Lloyds.html and others) emphasise him being a carpet fitter and (per his son) "working-class intellectual", being also a senior member of the U.K. Communist Party; of course nothing precludes a man having been both a carpet fitter and a publisher, but if both pertain to the same individual it's interesting how emphases can be employed for certain effects! Whatever the origin of the carpet fitter/ "working-class intellectual", U.K. Communist Party details, this description is repeated in basically the same phrasing in several online media sources, none of which seem to expand on any aspect.
There appears to be a death record for only one Edgar Wilfred Grimstone (1916-1986), and a 1916 birth record for him at Marylebone (mother Kenwright) which seems to be repeated in 1959 (same place); of course it's not impossible for two Edgar Wilfred Grimstones to have been born to Kenwright mothers, but such strikes me as quite unlikely. In any case, there is only a 1916 marriage record (at Wandsworth) for William J. R. Grimstone and Emily M. Kenwright that I can find, which must be the parents of E. W. Grimstone. A William John R Grimstone b. 1888 at St Giles, London, d. 1976, at Worthing, Sussex, presumably this man given the lack of alternatives and considering the dates. No probate record I could find. The 1901 census shows a William Grimstone b. London, 1889, with his parents, William (b. 1847, "laborer (general)") and Caroline (b. 1853, "char woman"), living in the parish of St James, Westminster.
In the thisismoney article above, however, Lord Grimstone mentions his father "died when (he) was very young", which would seem to run counter to the 1986 death. The 1986 E. W. Grimstone's probate record gives his address as Croydon, meaning it's likely he's the same as the publisher mentioned in the London Gazette; the issue, it seems, is whether or not a separate Edgar Wilfred Grimstone, the carpet fitter, father of Lord Grimstone, exists (on the evidence, I tentatively conclude not). Another possibility, I suppose, is that his parents divorced, and the man to whom Lord Grimstone refers as his father, a carpet fitter who died when Lord Grimstone was "very young", was his stepfather? I couldn't find any other marriages for Dorothy Y. Grimstone or Martin, though, which might explain this.