DS is 9 and wants to stay home and read his book rather than come for a walk in the park with DH and I. In fairness, it’s pretty muddy and soggy down there but I’m trying to shift the last bits of a cheery cold so I want to get out and about. We’d be gone for about 45 mins, DS has been left before whilst I pop to the corner shop in the rain for example (10-15 mins?) and is very trustworthy. What would you do?