British Airways serves MAN-LGW 7x daily Mon-Fri with reduced frequencies at weekends. Fares on this route tend to be very competitively priced for early bookers, as BA like to direct their Manchester-London budget traffic onto this route. Any competitor entering this market will face an incumbent with an attractive spread of timings throughout the day and with low-priced capacity offered. Plus, of course, competition from all the other Manchester-London travel options by air, rail and road.
In contrast, MAN-BOH is not served by air at all. By train this is a gruelling journey with day-return travel impractical. By car the route is tortuous, and also unsuited for day return travel. It is reasonable to suppose that a significant market exists between Greater Manchester and the Bournemouth/Poole conurbation with it's surrounding counties. When served in the past [admittedly with small commuter types but at high fares] the route acquitted itself well [think Dan-Air Link City, Metropolitan Airways and Eurodirect]. Add in the flexibility of a contemporary no-frills player able to attract VFR and tourist traffic as well as business travellers and we have a route with potential. I suspect there would have to be some rationalisation involving the nearby MAN-SOU route which is set for 9x weekdaily service this Winter [BACX 6; FlyBe 3]; however, I would contend that dominating the MAN-BOH route makes far more sense for a company such as Jet 2 than becoming a bit-player on MAN-LGW.
By the way, where did you see the Jet 2 application you refer to? Clearly, they have not yet announced sufficient work to keep the six MAN-based B733's occupied so it would be interesting to observe where else they have in mind.
Regards, SHED.