So...it can be done. But it’s not straight forward and you need a GOOD amount of time.

I checked in for my BA flight at terminal 2 and passed through security there. I was surprised how little there is going on at T2. Not a single flight was boarding so no airline staff to ask. There’s no information desk. And all of the terminal signs direct passengers to other terminals via the exit. I persevered a little though and found some stairs down to some bussing gates. And behold, there was a sign ‘bus transfer to terminal 5’ along with a request button to push. The bus came along in ten minutes and makes stops at T4 and T3 along the way.

I met my friend in the FANTASTIC little AMEX lounge within ‘Pontus’ restaurant and then made my way back. Again, this was a task. The drop off point I arrived at wasn’t the same place I’d catch the bus back. So I approached a passing SAS ground staff and asked where I should go. He said there was absolutely NO bus airside between terminals. And again, all signage directs you to the other terminals via the exit. I obviously knew there was so kept up asking. I found a SAS ‘service centre’ and the lady that helped me knew of it but had no idea where it was. She made some phone calls and found out the answer. It was similar to the T2 set up. Down a random set of stairs near a gate and then press the button to request the bus.

So for anyone travelling from T2 that has reason to go to T5 - follow the signs to gate 61 before passport control but after security and take the stairs down.

For those wanting to get from T5 to T2 - head for gate 10.

oh PS. The bus driver did not need to see a boarding pass for the transit and there was no further re entry security.