Why are house prices rising?

House prices are rising at their fastest annual rate for nearly three years, according to one of the UK's biggest mortgage lenders.

The Halifax said prices in the three months to the end of June were 3.7% higher than in the same quarter last year.

That is the fastest rate of increase since August 2010.

Martin Ellis is from the Halifax and spoke to the BBC to explain some of the factors that were pushing up house prices.