Visa Waiver

Yes you can do that, with a valid visa or visa waiver for Canada ... the 90-Day Rule (and the North American exclusion zone) only applies if you wished to return to the US after spending time in Canada - in which case the Canada time is counted in your 90-Day VWP allocation. No worries.

If you don't touch US soil on the return trip to UK . ie- Your flight does not transit a US airport.

#1 is wrong.

Time in xCanada after your initial entry into the xUS is included in your 90 days. It doesn't matter if you are going for a few days to visit, or 6 months to work. It also doesn't matter if you leave from xCanada, or come back to the xUS to leave. The total time must be 90 days or less.
Read this link from teh embassin in xCanberra (and it applies to all VWP nationalities).

What you plan would mean, by rule, that you overstayed your visit to the xUS, a breach of your entry via the VWP. Violating the terms of the VWP renders you ineligible to use it again.

If you never plan to come back to the xUS, it's no problem. If you do, it's potentially a large problem.
So to answer your question, yes, it's possible, but you may screw yourself in the process.

Let me elaborate. When you depart the US for Canada, your departure from the US is not recorded. You are still on the books (or rather, in the computer) as being in the US on a Visa Waiver. Once 90 days has passed, you are now listed as having overstayed, called being "out of status." Once you are on the books as having overstayed, you can never use the Visa Waiver Program again; you need a full visa. You will need a full visa even if all you plan to do is transit the US on the way to somewhere else, yes, even for a two-hour layover in a US airport.

If you are out of status for longer than 180 days, you cannot enter the US for 3 years. If it's over a year, the ban is 10 years. There is a way to demonstrate after the fact, that you did indeed return to England before the 180 days was up. But that won't negate the need for a full visa.

If you never, ever plan to set foot in the US again, not even for an airport transit, then you have no problem. Otherwise, yes, you have a problem.

However, if you can arrange your trip so that you go to Canada first, directly from England, no stop in the US, then the 90-day clock will not start until you set foot on US soil.

If you decide to get a full visa now, then there is no issue. The B2 tourist visa is usually good for multiple entry over 10 years. On each entry, you usually be granted a stay of 180 days.

Nope.

.

OK, so then if it is not possible to continue straight into Canada, would a detour to somewhere that is neither Canada not Mexico resolve the issue? Meaning, for example, spend 90days in the US, fly out to somewhere like Puerto Rico for a couple of days and then from there fly into Canada?

Puerto Rico is part of the US.

The rule is actually that you must have an onward ticket to somewhere that is not Canada, Mexico, or adjacent islands The site notes that Cuba is not always treated as an adjacent island. For the purposes of the Visa Waiver, it is an adjacent island.

You could go to some place in Central America. However, entry into the US is always at the discretion of the immigration official. the official might view two days in Costa Rica as a "visa run" and deny you entry. Or might let you in. If you fly from Costa Rica to Canada without transiting the US, you'd be fine.

edited to add: I just checked for the heck of it. Air Canada flies nonstop from Costa Rica to Toronto.

Edited by: nutraxfornerves

OK, thanks for the help!

Flying to xPuerto Rico to leave the US is like flying to xManchester to leave the xUK.