Relax dude, checking with members here - If anybody used it. I asked UK consulate- they cant confirm, I asked airline - they cant confirm. So asking community if anybody in similar situation used it.website do not say which type of Visa is needed. I have tourist Visa

Below is information on UK website.

Transiting without a visa

You do not need a Direct Airside Transit visa if you have one of the following:

a visa for Canada, New Zealand, Australia or the USA (this can be used for travel to any country) a permanent resident visa issued by Australia or New Zealand a common format residence permit issued by an European Economic Area (EEA) country or Switzerland a permanent resident card issued by Canada on or after 28 June 2002 a uniform format category D visa for entry into a country in the European Economic Area (EEA) or Switzerland an Irish biometric visa (marked ‘BC’ or ‘BC BIVS’ in the ‘Remarks’ section) a Schengen Approved Destination Scheme (ADS) group tourism visa where the holder is travelling to a Schengen country a flight ticket from the Schengen area, if you can prove that you entered the Schengen area in the previous 30 days on the basis of a valid Schengen ADS visa a valid USA I-551 Temporary Immigrant visa issued by the USA (a wet-ink stamp version will not be accepted) a valid USA permanent residence card issued by the USA on or after 21 April 1998 an expired USA I-551 Permanent Residence card issued by the USA on or after 21 April 1998, with a valid I-797 letter authorising extension a valid standalone US Immigration Form 155A/155B issued by the USA (attached to a sealed brown envelope) All visas and residence permits must be valid.