Thank you hmv.
I'm looking to fly from the US via LHR to AMS just before Christmas and the above links are helpful (although understand BA might continue to ignore them). I also emailed Public Information Service (part of the Dutch Government) and they also stated that for short transfers in the UK (less than 12 hours) a negative covid test is not required. Hope that someone who is able to successfully transfer in LHR to AMS in then next week(s) will post here to let us know that BA has updated /corrected its stance on negative covid tests for transfer passengers traveling to the Netherlands