There's a discussion on Petstreet about one member's experiences after winning a day shadowing an RSPCA Inspector. Also, see her fuller diary of the day. It's very interesting to see how we appear from "outside", in particular how difficult it is for other people to understand how the RSPCA's somewhat chaotic structure grew as the result of the decisions of local branches over a timespan of more than a century.
In our case we have a clinic, but no animal home purely because the branch committee of 50 years ago identified a welfare need for low cost pet care and negotiated a deal with Cambridge University to get cut-price treatments in return of use of the clinic for training new vets.
In the case of Stubbington Ark in Hampshire, the branch committee presumably decided they wanted a shelter and raised funds for one. HQ animal homes tend to be more strategically placed in that HQ will realise that there´s a problem with finding placements for animals in a particular region and build a home to fill that need.
Cambridge branch uses a combination of care at private boarding kennels, fostering by individuals and transfers to Block Fen which is our closest HQ funded shelter. The advantage of using private kennels is that (if we have the money!) we can increase the number of available spaces "overnight" rather than having a building with fixed limits. The disadvantage is that private kennels are not usually geared towards rehabilitating animals with behaviour problems etc.
Where there's a long-established HQ run home there is a tendency for the local branch to wither away because all the public interest — donations, volunteers etc. — tends to come to the home rather than the branch. In the long run that tends to mean that the branch can't afford to supplement the places provided by the home with fostering or spaces in boarding kennels. I suspect that having an active branch also improves relationships with other charities because they're more likely to meet us day to day. I certainly don´t get the degree of antagonism the Maidstone inspector seemed to find and we regularly come to arrangements with the local ferret rescue, Cats Protection, Blue Cross etc. if we have facilities & they don't or vice versa.
I´m afraid at the end it does come down to money. We've never yet been in a position where we were telling our inspectors to put down healthy animals, but a year ago we were very close to the point where we'd have had to. This is why it's so vital that we make a success of our new shop.