HELP! I can't seem to get a straight answer from the airlines at all. Can anyone help? I am flying from Hong Kong to Dublin via London Heathrow. I land in Heathrow Terminal 3 and connect directly to Terminal 1 for the Dublin flight. Does anyone know whether or not I need to clear immigration and customs? Can I NOT clear immigration and customs and proceed directly to T1 assuming that my bags can be checked straight through to Dublin? Tx~

You need to contact the airliens and determine if your luggage will be checked through. If the luggage is checked through yuo can stay airside (no immigration) and can make a connection within 2 hours.

If your luggage is not checked through you have to go thruogh immigrtion, pick up luggage, walk through customs, take a different bus to the next terminal and do the check-in and security thing all over again. I wouldn;t risk it with less than 3.5 hours.

Is this one ticket? Separate tickets? Partner airlines? Just random airlines?

You MUST go through immigration in London to transfer onto a flight for the UK or the Irish REpublic.

This is required whether or not bags are checked through to Ireland. If they ARE checked through, you do NOT need to collect your bags in London, or present them to Customs. They will be subject to Customs inspection (though there won't actually be any inspection) at Dublin

" If the luggage is checked through yuo can stay airside (no immigration) "

...is incorrect

You won't take a bus between T3 and T1--they are connected by an underground walkway which accommodates baggage trolleys if your luggage isn't checked through. Look for the signs after you exit the baggage hall. That part (walk from T3 to T1) takes only a few minutes. It's immigration clearance at T3 which eats up time.

You're getting more duff information here than you'd get if you relied on North Korean television.

Assuming your bags are through-checked, blow-by-blow details of International-to-Ireland transfers for passengers arriving on Cathay or Virgin are at http://tiny.cc/nHIgV

You're right, I gave poster crap info and, what is more embarrassing, I have done the sequence you describe. Hate to admit I'm that addled.