So embarrassingly I was on the Daily Mail website and found this story:
Patient dies after neighbour posted angry note on ambulance saying 'you may be saving lives, but don't block my drive' as paramedics tried to save him
(Daily Fail annoys me, patient death was unrelated note
)
Needless to say, I thought of this area of the forum. 
I've not copied the link, but essentially the ambulance was visiting a property due to an emergency (internal bleeding/vomiting blood) and parked across a driveway. They were only there for 30 minutes and when they came out they found this note.
Needless to say, I think maybe the author was BU.
Can't help but wonder if there was dog poo under the handles, bread on the roof and if the cheque had been cancelled....
I feel the need to clarify that I never read the Daily Fail so I'm incredibly embarrassed....