In relation to Indian airlines..

Red list travel ban countries
If you have been in or through any of the countries listed below in the previous 10 days, you will be refused entry to the UK.

If you are a British or Irish National, or you have residence rights in the UK, you will be able to enter. You must quarantine in a government approved hotel for 10 days.

Plenty of British Indians are free to come and go as long as they hotel for 10 days on arrival