I highly recommend anyone transiting through the UK to apply for the ETA especially with the current situation with the FAA it could happen again .All transit terminals at LHR are not 24 hours and its worth the 27 or so dollars because irs valid for a few years after. Without it you cannot go landside.
So I repeat everyone transiting even if its not required take ten minutes and apply for it. You don't want to be stranded in a detention center.
ETA is not a visa.
An ETA lasts for 2 years and is linked to your passport. If your passport has expired or changed, you’ll need to apply for a new ETA.
https://www.gov.uk/check-eta
Not a "a few years". 2 years maximum.
I have seen this explained before and will try to do so here. The ETA is permission to get on a flight to the UK, as mentioned above it is not a visa, and it is NOT permission to enter the country- you will still need to be cleared at passport control once you land. If something happens and you wind up having to enter the UK after having landed here (despite that not being your original intention), they are not going to deny you entry for not having an ETA, they will just process you as normal. The only purpose of ETA is to allow you on the plane. Once you are here you are processed by UK border force.
