Dave, avoid the Mr and Mrs plumbers they are the 3 month trained version of a tradesman. Possibly the best firm is Michael Clarke. More expensive but first class.
I worked with the husband and wife pair and the work looked like a joke. They fitted a basin waste by smashing the lid of a sewer inspection cover and filling the damage with silicone. The waste pipe had a dip along its length under the floor and will clog within 5 years.
Westmancoat, Pearman are also good firms. Of course, my Nephews business regularly sees a lot of plumbers in action. Most of the apprentice served plumbers are long gone now. My Brother retired as an advanced craft plumber 3 years ago. Specialist in lead solder work on roofs which has damaged his brain. Still recovering but lost memory coming now.