The Alan Good organisation
Alan Good was one of that vanished breed of tycoons, Captains of Industry, who controlled the landscape of British industry during and after the war, and of course long before, who by force of personality and financial legerdemain would buy-up ailing companies and assemble huge conglomerates that allegedly achieved synergy, economies of scale, and tax-efficiency. One of the more recent examples was Arnold Weinstock at GEC. An earlier instance was Alfred Mond who created ICI, Britain's biggest business at the time.
But as we all know, such conglomerates also have an eventual tendency to disintegrate, or to be swallowed up in their turn by an even bigger behemoth, and I can only think that one of these fates must have overtaken Alan Good's empire, as I can find nothing about him on the internet.
But by the middle of the war my grandfather Robert was certainly an engineering consultant and Ministry of Supply liaison with Alan Good (apparently always known as APG), and it's evident that my father William was a consultant too, as it was there that he met his future (first) wife Kathleen (Katie) Blunt who worked for APG as a secretary. I once heard William remark that things might have worked out better between them had they married considerably sooner than the actual date in May 1944, so that does impose a sort of timescale. But it doesn't tell us anything about his job there, much less any involvement with the Centurion development.