This implies that these 6 cities do not have enough demand for a B737 / A320 from London.
If a route from London cannot support 150 pax per day
Whoa, Whoa, Whoa, Whoa,
Just because a route cannot fill a once daily Airbus/Boeing does not mean the route cannot support 150 pax per day.
The NQY/LON/NQY route is a prime example of this, put a Y35 seater on it 4 times each day and the loads will average above break even, put a Y150 on it once a day and expect to lose money big time and very quickly.
Might we please get away from "the only way is loco" and get back to offering services at times when the travelling public actually want to travel.
That said I believe an ATR72 is an overkill for Carlisle, Carlisle needs a Y35 seater operation or below.