Origional plans for Brough, pre chimney, were an extended runway to 7300ft (at the same time as Leeds) and a new major airport to be built in thorne (though this was not thought to be needed until at least the mid 80's)
At the time i believe the services were doing ok, brough was quite busy with movements, this can be confirmed in the old Yorkshire Aviation News magazines from the time....
www.55hr.karoo.net/images has some in pdf format
Notable is that the 'Hull(Brough)' service to the channel islands was autairs best performing route in june 1967!
Brough would have been a far better airport than HUY, close to the A63 and in an urban area, could have been a great alternative to LBA pre DSA!
I dont believe the flights were split as i am sure HUY didnt operate any airline operations until the 70's? Though i think the flights were moved to Leconfield for a short time until HUY opened. Why Leconfield wasnt developed i have no idea, the RAF allowed use by civillian companies by then (it had become a maintanence station)