LonRes says transactions in prime locations in London dropped another six per cent when the second quarter of 2018 is compared with the same period of last year.
LonRes splits its analysis of central London into three zones - Prime Central London, Prime London and Prime Fringe, defined by different postcodes.
Prices across Prime Central saw a modest rise of 1.2 per cent in Q2 2018 compared to the same period last year - the highest annual growth since Q3 2015.
However, more substantial price falls were recorded in the Prime and Prime Fringe areas, down 3.9 per cent and 5.0 per cent respectively, comparing Q2 2018 with Q2 2017.
Across all areas, buyers paid an average of 9.9 per cent less than the initial asking price in Q2 this year, down from 10.6 per cent in Q1 2018. Some 52 per cent of homes sold over the period found a buyer following a price reduction.
Fewer transactions meant stock levels rose. Across the three areas there were 15 per cent more properties for sale over Q2 2018 compared to the same time a year ago.
However, the number of new instructions fell four per cent year-on-year.