I was a non-delinquent child who (ahem) explored empty houses with other tolerably well-brought up friends (we were careful not to cause damage by breaking in, as are the Marlows) so I didn't register that as at all odd. The pony strikes me as odder, yes, though I think that is meant to illustrate Peter's cluelessness--Nicola, slightly belatedly, realises that it's not on and might well be dangerous.
As to under-16s being left in charge, I don't know what the legal position exactly was in the late 1940s. In the early 1960s my 14 year old uncle was left in charge of my mother (aged 12) and their toddler sister while my grandparents worked night-shifts and this wasn't at all considered odd or irresponsible, though they were of a rather humbler class background than the Marlows. That's all I can offer anecdotally.
The parallel between Giles and Foley's reprimands is interesting: given Foley's hot but short-lived temper I imagine it's quite a different quality of ticking-off from Giles's icy fury, but it has much the same effect...
no subject
As to under-16s being left in charge, I don't know what the legal position exactly was in the late 1940s. In the early 1960s my 14 year old uncle was left in charge of my mother (aged 12) and their toddler sister while my grandparents worked night-shifts and this wasn't at all considered odd or irresponsible, though they were of a rather humbler class background than the Marlows. That's all I can offer anecdotally.
The parallel between Giles and Foley's reprimands is interesting: given Foley's hot but short-lived temper I imagine it's quite a different quality of ticking-off from Giles's icy fury, but it has much the same effect...