Hebrew Pronunciation in England

Hebrew pronunciation - I've always wondered why in Anglo-Jewry we write Beth Din, Beth Haim, etc, when the Ashkenazim here nowadays use s for final t, and the Spanish and Portuguese use t. Montanus' sixteenth century Latin interlinear translation of the Tanakh, using the Spanish pronunciation of Castille, uses th for t without a dagesh. Vossi, in his 'Rudiments of Hebrew Grammar', also in Latin, makes the observation, that in England (apud Anglos) t is pronounced th without a dagesh. If this is so, this must refer to the Spanish and Portuguese pronunciation. Vossi mentions b is always b, never v in the Portuguese pronunciation, as still used at Bevis Marks.