Having tried unsuccessfully to find a definitive answer to the above question on the UK visa and Heathrow sites, I would greatly appreciate your help.
A South African citizen is flying from Cape Town to Heathrow with BA (arriving at T5), transiting straight through on the same day and flying with Virgin (from T3) to New York (i.e. she is not leaving the airport). The flights are booked on two separate tickets and she has a valid US visa.
As she is changing airlines and is not booked through on one ticket, she will need to collect her luggage after the BA flight before going to T3.
Could someone please advise whether she needs to get a landside or airside transit visa? I am aware of the DATV concession but can't establish whether or not this applies to her. Just in case it makes any difference, she is also in possession of a recently-granted UK partner visa, but will only be going into the UK when she leaves New York in December.
Many thanks for any advice.