Looking for my father (Thessaloniki)

I am looking for my father who moved to Greece Protected content ago. He is a 73 year old British expat originally from the Midlands. Does anyone have any ideas how I can start to look for him. All I know is that he lives in Greece, had remarried and has a son aged 40. I have tried the British Embassy in Athens but have received no reply. I would greatly appreciate any advice.