Quote
TO be LET for the Summer Season. — Respectable FURNISHED APARTMENTS, a short distance from Portsea, and within ten minutes walk of the Cosham Station of the London and South-Western Railway.
Address X.Y.Z. Coach and Horses, Hilsea.
— Hampshire Telegraph, Saturday 25 May 1850
Work to build Cosham Station only started September 1849, so maybe somebody saw an opportunity?
My understanding is that “X.Y.Z.” is a privacy veil. Letters addressed to “X.Y.Z. Coach and Horses, Hilsea” would be held for later collection, so “X.Y.Z.” didn’t have to reveal their real name in the ad. So in this reference, the pub is probably being used as a mailing address.