Re:
Thanks for all the comments. I have now used it a fair amount; carrying a few beers for a snooker evening and a few ordinary shopping trips. It is comfortable but twitchy. With a load in the box you do need your wits about you as once you’re turning it really wants to carry on turning!
It was the ‘stealth’ aspect of a really nice frame hidden behind a shopping box that inspired me too. There is a gentle off road bridle path near me so I will probably have a go on that at some point, but probably unloaded at first... I’ve not heard of ‘mountain mayhem events before, so if they are an ongoing thing I might be interested, depending on where. I live near Cambridge so not great mountain bike territory unfortunately!