At some time in the sixteenth century, a small timber-framed building existed on this site. It was likely to have previously been a medieval market stall, or even a shop. Deeds from the fourteenth century show a mix of tenements, market stalls and shops in the area. The current Horse & Groom was originally known as the lower Rose & Crown. From the records at the Licensed Victuallers' Association, the first licensee was listed in 1719. It is more likely, however, that the pub was there much earlier, but no records exist to prove it. The first licensee was one Peter Tillier, who was the tenant for two years.

In 1769, the lower Rose & Crown was sold to a Henry Reddington for 271 pounds and 17 shillings.

When the name was changed to the Horse and Groom in 1792, the recorded licensee was Richard Knight. At this point, the property was in the ownership of one William Foster, a Windsor brewer. The mortgage of £250 at that time was made to a James Dauncey.

In 1837 the pub was sold to Neville & Reid as part of the Windsor Brewery Estate.