Just completed my trip. Here is my experience.

My UK visa recently expired & I have not had the time to get it renewed since I've been traveling pretty much non-stop over the last couple of months. I had an option to take a 12 hour layover in London & wanted to go out & meet up with some friends. My travel route was BOS-LHR-CDG-DEL. I was to land at LHR at 7:30am & my flight to CDG was at 7:35pm the same day. Then I was spending 3 days in Paris before flying back to DEL.

I landed at Terminal 3 & went over to immigration. The officer there was a young girl who had no clue what the TWOV scheme was. She said there was no way I could enter without a visa. I showed her the TWOV document available on the UK Government website but she said she had never heard of it & had to ask someone senior. The senior officer came over after she had briefed him & said that the scheme was only applicable to those who were residents of the US. I politely pointed out that I thought the document said it was for anyone who had a US visa & said nothing about residency. He then changed his stance to the fact that I was not eligible since I was not flying back home to India & was going to Paris instead. I again pointed out that the document said that it only mattered that I had a valid visa for my destination, which I had. He then again changed his stance to the fact that it was the officer's discretion whether he would allow me to enter or not. He was extremely rude during the entire exchange & it became pretty clear that he was not going to budge from his stance. I thanked him for his time & went back to the transit area to go to Terminal 4 for my connecting flight.

When I reached Terminal 4 I was walking by the immigration area on my way to security & decided to try my luck again. I went over to the counter & handed over my passport to the officer. I asked him if I could avail of the TWOV scheme since I had 12 hours in transit. He asked to see my boarding pass for the LHR-CDG flight & then stamped my passport allowing me entry for 48 hours. I was through in under 2 minutes.

It was officer discretion at the end of the day. The first officer was rude & being difficult while the second officer just looked at my passport & BP before allowing me to enter.