Undone the work of not one but two visits from the faerie.
One was a small metal staple poking in through a 16-month-old tyre/tube combo, which have done at least 2500 miles without needing anything but a bit of air now and again.
The other was a 4-month-old self-adhesive patch that had given up its airtightness. So on getting back from holiday, I looked in the shed, and found the Windy sitting down at a funny angle. Note to self - patches are for get-you-home, not leaving in tyres for months on end.