In the afternoon I suggested we have a look at Coombe Abbey Country Park about four miles away. As I started to get the tandem out, something felt wrong - the back tyre was completely flat. The tyre has a Kevlar lining, also used in bullet-proof vests, but this is no match for a hawthorn. At least the source of the problem was easy to identify, so it didn't take long to fix and we were ready to go.