Captain Underpants

L wants to be Captain Underpants.
It’s School Book Day tomorrow and he is determined to make his appearance in the school playground in nothing but pants and a cape. Torrential rain is forecast and I am equally determined that he won’t – or will have to wear his sister’s too large leggings or some 2-3 year-old but still super-stretchy ski thermals in a cupboard rummage.
This will of course ruin the Capt Underpants effect, making him look merely mad as opposed to call-social-services-now.
My reasons are not entirely born out of maternal care - despite putting away vast quantities of food, he is also painfully thin with chicken wing shoulder blades and has a large molluscum on his upper arm.
I thought we'd made progress when he discovered a battered cowboy hat, chaps and waistcoat combo. But the only cowboy book we can think of is Cowboy Baby and that is ‘too babyish’ for a seven-year-old. Still, last night, he went to bed in his cowboy outfit. The battle recommences this evening.