So is the consensus that it is possible to get from T1 to T2 airside without going through immigration? There seem to be two opinions expressed here.

I ask because as a Canadian I get a stamp in my passport each time I pass landside, and the Irish stamp is HUGE. takes up half a page, and I'm afraid they'll fill up my passport if I take ex-DUB flights to the US from the UK.

Also, if I fly Ryanair into T1 can I board a BA flight to the UK that departs from T1 without clearing immigration? A lounge receptionist told me I can't (something to do with p2p carrier) but that seems illogical.