When Paul says "With a ladder and some glasses, you could see to Hackney Marshes, if it wasn't for the houses in between," he is quoting the old music hall song "If It Wasn't for the 'Ouses in Between" made famous by Gus Elen.
When Paul sings "She looked so neat and nimble, O" over the garden fence, he is quoting the traditional English folk song "Dashing Away with the Smoothing Iron."