Simulator
Thank you all for your replies.
The reason I asked the question is that I was in a flight simulator recently for my bi-annual check and I was faced with a single hydraulic failure while flying towards the London TMA.I did declare a PAN after actioning the QRH(checklist)and for all the reasons you have come up with I believe it was a correct call.
In the debrief the check Captain queried my PAN call.He stated that he had never heard of a requirement to inform ATC by means of a PAN.He asked me for a reference and I replied that I thought it was in the AIP.
Hence the query.
Ikarus