Just bought - ‘cos of the way it looks (and its general quality/spec).
My wife had a Courette in the early’80s.
I didn’t realise the name had been used by Carlton before.
In fact since 1955, with mixtes from 1960.
Great details here - http://carltoncycles.uk/carlton-courette/
This would originally have had drops, but apart from the bars and brake levers, and pedals, it seems to be all original.
The alloy rims (Weinmann) were a catalogue option. Curiously the hubs are not a pair - front Normandy and rear Resillion. Factory mistake or ‘that’s all we’ve got’ or one replaced later? Probably never know.
Now the considerations of upgrades - don’t think a double chainset with only a 3 tooth difference is optimum!