Esq as a postnominal indicates that the person is a land-owner (is esquired of an estate - is a squire) and is an honorific for magistrates and the like. Its one rung up the ladder from a plain Mister. Similarly a Reverend who has an degree is slightly above the general plebs. I'm not sure who gets to go into dinner first but they, and their lady wives, both would out-rank a plain Mister and his Mrs. Regards