Upvote:1
What passport are you on? I assume you are on a South African passport.
Since Ireland is a part of the Common Travel Area, my understanding is that you require a full visitors visa to enter the UK en-route to Ireland.
See https://www.gov.uk/transit-visa/visitor-in-transit-visa
This is on the Visitor in Transit Visa details page
Travel to the Channel Islands, Isle of Man or Republic of Ireland
You need to apply for another type of visitor visa if youβll be travelling to the Channel Islands, Isle of Man or Republic of Ireland.
The issue is because Ireland is part of the Common Travel Area, the flights are seen as pseudo-domestic flights.
Some other South Africans will insist that a transit visa is all that you require. I believe that is because they hold valid residence cards.
Source: I am a South African national residing in Ireland on a valid work permit.
See attached Timaticweb Documents: