As I suspected, another debatable question and 'correct' answer!
I wondered if 'Lifeboat' was just supposed to mean the larger offshore vessels OLB.
Especially as the REAL correct answer for an Inshore Lifeboat , ILB, was not offered; i.e. 40 knots.
Nick; I think you mean the 'E class'.
The Mk 1s with Steyr engines had a top speed of 35knots, the Mk 2s with Volvo engines 40knots. There are three E Mk2s in service on the Thames; Tower and Chiswick stations and one in reserve.
Since 40Kn was not offered as an answer I went for the offshore boats maximum of 25Kn.
Wrong Grrrrr!😠 So I checked up.
Cheers, Doug😎
https://en.wikipedia.org/wiki/E-class_lifeboat