Originally Posted by
craigthemif
However, passing security twice in one day is something most people try to avoid. Especially if you have a short-ish connection and might run into a queue.
But I assume that, even if there is an airside bus, one still has to go through security at the new terminal after using it - just like transferring LHR T3<>T5 for example.
If there were a dedicated U.K./Ireland --> onward connections bus, that could in theory bypass security, but from c-w-s' description I highly doubt there is.