The bathroom "fitter" with the best reviews is quoting by far the cheapest.

JadeHighland

We have a small bathroom around 2.5m x 1.6m and we are looking for it to be completely ripped out and done again, including moving piping work. We got a quote from two general builders and they were charging just over £6,000 for labour. Another person is a "bathroom fitter". He spent the most time measuring things up (other builder didn't bring his tape measurer), and came across the best as he answered questions we had, came up with solutions etc. 

I believe, compared to the others, it will just be him doing everything; tiling, electric, plumbing etc. He's charging £3,950 for labour and £280 for waste removal. By far his has the most reviews on Google and is even on Houzz. He said he'll be available in 6-9 weeks where the others are saying 3-6 months. 

Is that too cheap? He filled me with so much confidence but then, ironically, priced well below the rest. 

MysteryMe

Not saying it's applicable here but as a general due diligence point, ask for references of people locally who he has worked for and check with them. There are many false reviews online.

You obviously want the electrical he does to be checked by a qualified person, assuming this guy is not a qualified electrician. Ask him about that.

It may be the general builders quoted high as they were not fussed about doing the work, used to be done as a polite way of them saying not interested. Or maybe they are VAT registered and the bathroom fitter is not.

sheenas

As someone who has done a few bathrooms the quotes make sense. A general builder will hire people to do the tasks plumbing, tiling etc. the guy with reviews will do most tasks himself hence measuring. Understanding the tasks and what the quote includes is key. The builders will generally take the work and charge extra for every little change and reduce cost as much as possible for their not your benefit. 

Albermarle

We had a little bit bigger bathroom done, everything by one guy.
He also included some items in his quote and we bought some separately, so not an exact comparison, but the labour cost was closer to your lower figure of £4K than £6K.
If I remember rightly it was about 8/9 days work, but he was very experienced and efficient.

You obviously want the electrical he does to be checked by a qualified person, assuming this guy is not a qualified electrician. Ask him about that.

An interesting point as in our case the bathroom fitter was an ex plumber/heating engineer by trade.
However from an electrical point of view, he only fitted some new lights and extractor fan to existing connections. The only new connection was to connect the low power dual fuel towel radiator, which I think he did by connecting it to an existing ring in the loft room.
Not sure if you really need a proper electrician to check that sort of work, or not.