Just to update: Hubby eventually found how much. In case it might be of help to the other forumers in a similar situation, price is £23, plus an admin fee of £5. And as already mentioned, an appointment with the consul is necessary, by which the earliest slot that was free was not until the 6th of May, and with a 2-3 weeks'' processing time--so, a siginificant wait to factor in when planning (for non-British passport holders or companions of one, that is).
Ta.
(Mods, feel free to delete thread if this has been already addressed elsewhere in the forum.)