The media have been banging on about it for years, including such unlikely characters as the Mail, but it's only caught fire since the ITV drama.
Like Charlie, I've done comms work for PO over the years, including for Vennels and Angela Van Der Bogart, the chief baddies in the TV show. We got involved because there were a couple of TV programmes about it re: potential miscarriage of justice. The PO line then (6/7 years ago) was that the Horizon system wasn't faulty, at all, and even if it was, which it wasn't, then it could only have affected a handful of cases, which it hadn't.
Vennels always struck me as a Theresa May type. Serious. Sensible. Proper. Cautious. Not presumably that cautious, or she wouldn't have got where she had got to. And like May, I suppose, with a nasty fucking streak at the heart of her.