At the moment there are 6,270 Postmasters and I suspect, unless a lot of new Post Offices have been built, that number has been there for a long time.
When you suddenly get 100s of fraud cases somebody should should say "What's going on?".
We have 11,000 staff and if the same type of case came into our department on a regular basis we'd be asking questions and it wouldn't take 700 or so.
eg Over the last 13 years I know of 5 staff who have been found guilty of fraud (illegally filling in time sheets) but if all of a sudden we got 5 in a month and staff vehemently denying it we'd have to ask questions.