I've trawled through the web and have found a few differing answers to my question.

I have a working holiday permit in my passport that says 'does not authorise re-entry'. I would like to know if I go to the US for a day or a couple of days, whether I will be able to re-enter Canada. I have my visa waiver for the US and at the border I have visited - Canadian - they told me that the note on the permit simply means that it does not allow reentry alone but will do so with my passport. I'm just worried that it'll be all very well and good going into the states, but that there may be a problem coming back.

Some people's accounts are that it is fine to do this, others are that there can be problems.

Is there a definitive answer?

Thank you.

The 'does not authorise re-entry' statement on a work permit refers to the fact that a work permit is not an entry-visa. To re-enter Canada, the holder of the work permit must ensure that they have an entry visa that permits this or that they are entry-visa exempt. A UK national (among other countries) is entry visa exempt.

Thank you for your answer David!