In post 124 I have identified a quick way to get Avios into your account. I've found another.

Currently there is a promotion to 22 December 2022 where you get 5 Avios per pound sterling at Prêt à Manger, generally known as Pret, the UK sandwich chain. This may or may not be continued past 22 December. It works by registering one or more credit cards with Avios, and if they detect an eligible transaction at Pret then they intercept it and credit the Avios automatically. And this actually works.

In my case I had pre-registered a card on / about 20 October 2022;
1) On 1 November at Pret in Gatwick South airside I bought £4.20 worth of snacks. I photo'd the receipt, just in case.
2) On 3 November I got an email from [email protected] with the subject line "Your 22 Avios from Pret A Manger are on the way"
3) On 4 November I duly received into my BAEC account 22 Avios.

So they rounded that up, since I should really have got 21 Avios but I'll desist from contacting BAEC about that overpayment.