I used Darren last week too and he is as described, despite having a broken arm! He fixed my toilets.
However, one thing I'm not sure about is if he does Gas Safe stuff himself. I haven't been able to track him down on the Gas Safe website and his website doesn't work any more - http://www.dchplumbing.com/About-Us.html
We had a blocked drain and not even a straightforward one. Darren came as soon as I rang him. He even had to come back because it needed more attention. Darren was professional, punctual and reliable. Highly recommended.