Recently we had a family funeral where a friend of the family flew over from California. He tested negative before flying and likewise when he landed here in the UK.
The funeral was on Friday so he arrived in UK on Thursday. His last test (all of which were rapid lateral flow home tests) was on Saturday and this was negative.
He arrived back in the states late Sunday night and was pinged on Monday evening to go get tested, which he did and it was positive.
He has since notified those he was in contact with at the funeral and for safety’s sake everyone has done a lateral flow test.
It appears that someone on the flight to UK on Wednesday/Thursday was either a carrier or had Covid 19.
If you want to know about guidance for Rapid lateral flow home test kits click on the link below.