Hummingfrog,
I stand corrected, the A139 can do the same job as a Sea King/S61/S92/Super Puma L2 IF it has a lifeboat following it around, as in this case. In other cases it definately can't.
I am not against a mixed fleet, providing they are mutally supporting, but to put all your eggs in one basket by using a new small type to cover from Wattisham to Culdrose is a surprising choice. If there was a large type, such as the S92 at Lee and a A139 at Portland I would agree that it was a sensible mix.
I presume you are talking about downwash when you say that smaller types are better for kids on lilos. Well looking at the A139s rotor size and its weight, the downwash will be about the same as a Sea King or S61. In any case, if downwash is a problem, such as on calm days, hovering higher usually solves the problem and gets you out of the spray.