Misc: A male horse is called a...?

Questions

What was the title of the follow-up to the television series Please Sir?

In comic literature, what was the name of Billy Bunter's sister?

Which country other than Scandinavia, American coastline, Iceland and Greenland has fjords?

In which English town is the Headquarters of the S.A.S.?

In which town is the British Army's main prison, known to all soldiers, past and present, as The Glasshouse?