Thanks @Hardbackwriter
Gosh, on point a) - I think all it would take is a data-savvy, pushy journalist to deduce a fairly sensible estimation for this. It also got me thinking about geographic allocation of positive cases. When patients catch covid in hospital, I wonder where the positive case is allocated to - home address? hospital address? wonder how that is counted? it is probably buried in the NHS data disclaimer - I must dig around for it. Although - probably not a very meaningful impact in geographic allocation. It just got me thinking... Remind me a bit of the university student cases allocations in Autumn.
On point b) - reading through the data description, it would actually be incredibly easy for this data to be gathered and published. They are already gathering and including patients who test positive in hospital after admission but I suspect this is a political bomb as I suspect you could potentially deduce hospital transmitted infections. Which would cause a political and media frenzy if (when?) it occurred.
But the way the data is currently reported, you couldn't really spot a hospital outbreak with certainty if it happened. If they indicated those who tested positive in hospital as opposed to arriving with positive covid, (its just a boolean flag), it would be pretty clear or at least easy to identify possible hospital outbreaks.
Although the poor NHS - I think they are under enough pressure without that scrutiny. It's bound to happen at some point (if not already).