Theoretically no. However, because of increased security in recent years, airlines insist on acceptable photo ID before they will allow passengers to board a flight. The most acceptable form of ID is a current passport. If you contact the airline that you intend to travel with, they will tell you if they are prepared to accept any other type of photo ID.
Not from Northern Ireland as it is a part of the UK.
You do not need a passport to fly from London to Newcastle-upon-Tyne, as both locations are in the UK, however it is always best to take your passport with you just in case.
Yes, always.
No you need a passport.
Yes, you require a passport to fly to London Ontario from England. Similarly if you fly to London England from Manchester via Hong Kong you will need a passport +++ Not sure why you'd fly from Manchester to London all of 200 miles away, via Hong Kong! No, you don't need a passport to travel within the UK, BUT the airports demand ID for security, and your passport is usually the most reliable.
It is regarded as an internal flight, but you should bring a passport with you any time you are flying.
No, unless you are stopping at the US.
Although both Greece and UK are in the European Union you still have to show an up to date passport in and out of both countries.
Probably. You do not need a pasport but you do need photographic identity. Check with the airline.
London
No, you shoudn't because it is part of the United Kingdom.
Yes. You need a passport to fly anywhere.