I have Stamp 4 on my IRP card in Ireland(formerly GNIB) and working full-time here. I am traveling from Dublin to Delhi via Heathrow Airport in London and would be changing terminals at the airport.
So, my question is, do I need to apply for a UK transit visa. My colleagues have gone via the same route and they said to me that a UK transit visa isn't necessary if you have an IRP card but just wanted to make sure.
You might have a look at the information provided by London Heathrow Airport on their website. They do have a personalized guide (you enter arriving flight number and leaving flight number, and it will tell you how to do the transfer.
If that does not answer the question, you might contact the immigration services at LHR; they definitely should know what you would need.
It seems to be possible (if needed) to get a 24 hour transfer visa at arrival (but for that you will have to prove that you are indeed a transfer passenger.
Finally, if your trip is on the same ticket (booking reference), you may also check with the airline.
Have a good flight!
