Darren came to quote for the work and worked out what the problem was. He also fixed the problem at the time of the quote, saving me a lot of time. So far the problem seems to have been sorted (and we have had a lot of rain).
Overall, I would highly recommed Darren, he is professional, friendly and has solved my problem. I would have no hesitation in hiring him for further works.
(He actually charged £30 for the works but this website won't allow that figure to be put in)