I imagine this is the favourite for Percy’s death. There seems to be no image available of any PR and I guess he was buried closer to where he originated.

GR England & Wales deaths 1837-2007
First Name Percy H
Last Name Prosser
Gender Male
Year 1955
Birth Year 1885
Birth Month
Birth Day
District Ross
County Herefordshire
Country England
Volume 9A
Event Quarter 1
District Number
Page 96
Line Number 44

As far as I can see the only other candidate is this,

GR England & Wales deaths 1837-2007
First Name Percy H
Last Name Prosser
Gender Male
Year 1950
Birth Year 1886
Birth Month
Birth Day
District Birmingham
County Warwickshire
Country England
Volume 9C
Event Quarter 4
District Number
Page 321
Line Number 11

However, there is an Ancestry National Probate Calendar entry which indicates that this was a Percy Herman PROSSER who died 19 October 1950 so unlikely to be relevant despite one of the children probably settling in Birmingham.