Hi Alf
If you start from Stratford Park, go up the hill (Stratford Road)and then turn right you are then on the road from Stroud to Painswick, Beeches Green. On the right of that road as you walk towards Stroud there is Catholic Church/school. The school is called Rosary School. If you walk past that to a road junction and turn right onto Merrywallks, the bus station was accessible on your left (it's all changed now) and on the right quite high up off the road you can see the Catholic buildings. If you carry along Merrywalks you walk under a viaduct, towards the railway and canal. At that point you will be on Butterow, where Rodborough House was situated.
Are you talking about the Rosary School do you think? Or does my description of your walk make things any clearer?
You could perhaps contact Gloucestershire County Council, as the home may have come under their jurisdiction, rather than Stroud.
There was a large house called Stratford Lodge on the corner of Stratford Road which is now a Premier Inn that could have been the place you are thinking about. Go to
http://www.premierinn.com/en/hotel/STROLD/stroud for a photograph of it.
There is a Stroud Local History society which you can google, I don't know if they can help you.
Lizzie