Does this exist? "Rosewood Boarding Kennels"

Looks like a scrapyard on satellite

part of the school? something else here?

part of upton hospital or something else?

This place is definitely PERTH AVENUE 415, so something seems wrong about the surrounding streets...
https://www.karlstorz.com/gb/en/united-kingdom-slough-berkshire.htm

survey what this building is

Is this postbox still here?

Hetherden Hall?

https://www.wikidata.org/wiki/Q15223447