I am flying LAX BOS LHR AMS LHR leaving LAX at 10AM on Monday pacific time.
2 days before the start of my trip is now (Saturday).
I need to do a (will use £19 Chronomics) test 24hrs before I set off due to the arrival into AMS (BA requires that test even though not entering Netherlands. So I will do the test on Sunday so it works for both.
The UK arrival Pcr will be a Randox one as soon as I arrive LHR second time, and into the Heathrow drop box so hopefully out of quarantine Tuesday when result arrives.
So, no extra test.

The one concern I have is a possible PCR positive. I recovered from Covid in November so viral fragments likely to remain. US entry was on proof of recovery rather than a test.