I am an Indian passport holder with a US visa & am looking for information on whether I would be able to transit through the UK without a visa.

Little bit of background on my situation. I had a 10 year UK visa that expired recently. I applied for a new visa about 3 months ago but due to the backlog the UK Embassy is currently facing in India at the moment, my visa has still not come through. I leave for the US in 3 days so there is little to no chance now that I will get my visa in time.

My original plan was to travel DEL-JFK on the 1st of August, JFK-LHR on the 7th of August, stay a couple of days in London, then fly LHR-CDG on the 10th & finally CDG-DEL on the 13th. Now that my UK visa has not come through in time, one option is to change my LHR-CDG flight so that I leave on the same day as I arrive in the UK. However, since I am on separate tickets, I will still require to go through immigration so that I can collect my bags & check them in for my next flight.

I read somewhere that if I have a US visa then entry to the UK is allowed for a 48 hour period & is based on officer discretion at immigration. Not sure if that is accurate or not so am looking for anyone who has experience in a similar situation.