The HomeOwners' Alliance says it has identified what it describes as "the UK's best performing agent" based on how much it achieves above asking price for the vendor in any particular sale.
HOA names Roy Brooks of Dulwich as achieving an average of almost six per cent above asking price over the six months to the end of February, netting clients an additional £36,064 on average.
Wilson Heal in Amersham, Cockburn at Mottingham in London, Christopher Edwards at Pinner in Middlesex and Simmons & Sons in Basingstoke were the other agencies in the top five.
By contrast it says many prime central London estate agents - in a market suffering badly because of Brexit and stamp duty - have had to agree sales at 10 per cent or more below their vendors' original asking prices. HOA does not name any agency in that lower end of the league table.
The alliance, which has developed an online tool that it says can be used to check agents' performances - called EsatateAgent4Me - also names Wolfs of Harborne in Birmingham Andrews of Bristol, Loveitts in Coventry, Preston Baker of Leeds, Venmore in Liverpool, Harrison's of Urmston in Manchester, and Pattinson of Newcastle as 'best in their cities' for achieving over asking price for vendors.
The results were based on an analysis of 44,000 'searches' by the tool in February, each of which tracked agents' performances over the previous six months.