Plumbers in South London work out at roughly £55 to £70 an hour. That is an estimate with its working shown rather than a measured rate, and the reason matters more than the number.
The UK figures underneath the London estimate
Checkatrade puts the UK plumber hourly rate at an average of £50, inside a range of £40 to £60, and the UK day rate at £350. Those are cost-guide figures and exclude VAT, so a homeowner quote built on them normally lands a fifth higher.
Where the London figure comes from, since nobody measures it
The bracket above is constructed, and it is worth saying so, because plenty of pages present theirs as observed. What the published evidence gives is a direction of travel, not a London rate.
Housekeep, a London operator publishing dated guides that split London from the rest of the UK, puts London at around 20% above the national position. Checkatrade confirms the same direction from a different angle: London labour on fitting a toilet runs £50 to £200 more than the North. The £55 to £70 above is Checkatrade's UK range lifted by that documented premium, and it should be read as a bracket to test quotes against rather than a rate anyone has published.
The figures circulating at £65 to £100 an hour for London come from aggregator and contractor sites with no methodology and no publication dates. Nothing dated supports £100 an hour, and a quote built on it is worth challenging.
An hour is the most expensive way to buy a plumber's time
Checkatrade's published day rate works out around 13% below its published hourly rate, and the answer on plumbers' day rates does the arithmetic. The short version: it is a volume discount, because a plumber staying on one job saves a second lot of travel, parking and dead time.
The consequence for you is a booking decision. If the work runs beyond an hour or two, the hourly rate is the wrong basis to be quoted on, and asking for a price for the whole list will usually beat asking what the rate is.
The first hour is not the same thing as the hourly rate
A booked, non-urgent visit carries a call-out charge of around £60 on Checkatrade's scheduled-visit figure. A same-day or emergency visit runs £110 to £180. Whether the first hour of work sits inside that charge or is added on top varies between plumbers, and no authoritative source states a norm, which makes it a question to ask rather than an assumption to make.
In practice the realistic minimum for turning up and doing something small is £60 to £120 for the first hour including the call-out.
Emergencies run up to double
Checkatrade puts out-of-hours and emergency work at up to twice the normal hourly rate, plus a call-out charge on top. The fixed weekend and bank holiday uplifts quoted elsewhere are not published by any dated source, so treat them as illustrative.
The practical consequence is that a job which can wait until Tuesday morning should. A leak you can isolate at the stopcock is a scheduled job; one you cannot is an emergency, which is a good reason to know where your stopcock is and whether it turns.
What to establish before booking
Ask four things on the phone: the hourly rate, the call-out charge, whether the first hour is inside it, and whether the figure includes VAT. Published cost guides exclude VAT and most homeowner quotes include it, so a rate quoted on one basis and compared against the other is a fifth out before anyone has picked up a spanner.
An estimate you can interrogate beats a number you cannot.