Flying Venice-London - Immigration upon arrival?

One part of the previous answer is wrong.

When you arrive in London from SFO, you will not go through customs and immigration. (You got it right, the previous poster got it wrong.) Follow the signs to Flight Connections. If it is on the same airline, nice and easy. You will have to go through security again.

Go to the Heathrow Airport Flight Connections, plug in your flights, and it will give you step by step instructions on what you have to do as well as the minimum suggested connection time.

I always allow at least an hour for immigration. Then there is security. So get to the airport at least 2 hours or slightly more before your flights in Venice.

Here's how it will work

SFO-LHR: No Immigration at LHR, follow flight connections (Unless you have to claim luggage.)

LHR-ZRH: Immigration into Schengen at ZRH.

VCE-LHR: Exit Immigration out of Schengen in Venice. Immigration at LHR.

LHR-SFO: Immigration back into the USA in San Francisco.

You will go through airport security at LHR when changing planes to Zurich, in Venice when flying to London, and in London when flying to SFO.

Addendum: I see the previous poster deleted his post.

Thanks Frank, I sincerely appreciate the advice! I'll make sure to allow plenty of time before & after the flight out of Venice.

A follow-up question, if I may... I read something about needing to show "proof of financial sufficiency" when entering Schengen-area countries. After landing in Zurich, I'll be in Switzerland for 3 days, then catching a train to Milan, thus beginning a week in Italy.

Will the "financial resources" requirement apply to me, or is it only applicable to long-term visits? If it does apply, what sort of evidence will I need to bring with me?

In addition to the immigration and border controls outlined by Frank there will also be Customs checks at
SFO-LHR: At Heathrow if you have to claim luggage (are the two flights on the same ticket?)
LHR-ZRH: At Zürich
VCE-LHR: At LHR.
LHR-SFO: In San Francisco unless you are changing flights somewhere in the US before SFO.

All should be walkthroughs unless you have something to declare or you draw the short straw, except at SFO or your US layover. US Customs can be all sorts of fun, and you will have the Ag inspection too.

Mecha, I've been grilled for a return ticket entering England, but never a question for Schengen area. They often ask what hotel or duration of stay. If you pre bought the ticket to Italy to save money, I'd have that available to show.

I don't mean to be either offensive or unfair to civil servants, but I have been to Europe enough times to observe that minorities or people who stand out (say, dreadlocks) are often subject to extra scrutiny. I mention this because you asked for advice, not because it is certain to happen.

Nigel,

Thanks for the input re: customs. My SFO-LHR & LHR-ZRH tickets are separate, but I will not be checking baggage, so I should be able to stay airside. I appreciate the warning about US customs at SFO!

Tim,

Thank you for the advice; it's certainly welcome. I'll plan to have tickets/confirmations at the ready, just in case.