Highflight,
Are you suggesting that Cessna did not certify the aircraft with the correct figures in the first place or have TAG/Blink asked Cessna to do runway analysis especially for a surveyed EGLK.
I think it would be very unusual to revise the field performance, more than likely they would if there was any room for improvement they would increase the MTOM to make the foot fit the shoe, that would be to the benefit of all operators.
Cessna have previous in doing this with the CJ3 & the Sovereign from memory