Eaglestar,
This is indeed alarming. General advice given to pacemaker patients is that they should not pass through metal detector gates if possible, however they or their pacemaker will not come to harm if they are made to do so. The action of passing through a magnetic field may temporarily place the pacemaker into a testing mode, but normal device function will return once they exit the field. The patient may be aware of a temporary increase in heart rate during this but it is not dangerous and certainly should not be permanent. There are no reports in the medical literature of such actions occuring (and believe me any interested doctor would love to write up such a paper, a recent report of IPODs potentially causing interference gathered much media attention but has since been proved to have been somewhat flawed), and pacemaker manufacturers undertake extreme testing to ensure devices are well protected from accidental magnetic field or RF exposure.
What was the outcome with the your g/f's Grandad and his pacemaker? ie.
What symptoms did he experience and when?
What actions were performed to confirm a pacemaker issue? - What was found and how was it dealt with? (surgical replacement / reprogramming / lead repositioning etc.)
Who in the UK is aware of this? GP / Pacing clinic / Cardiologist / Pacemaker manufacturer / MHRA?
I work in healthcare in the UK and specialise in Pacemakers / ICDs. Please pm me if you'd prefer. There are a couple of points here which suggest the full story is not known and clarification is needed before you begin action which may be expensive and unnecessary.