The firm, which this morning revealed a surge in activity during the first three months of the year ahead of the government's stamp duty surcharge, said it would be "taking a cautious view of the coming months", in case the UK votes for a Brexit.
If there is a slowing in activity, it will come on the back of a 30 per cent surge in house exchanges in the three months to 31 March, compared with last year. This was down to a combination of "depressed" transactions in the run up to the general election last year, and the stamp duty surcharge.
Chief executive Alison Platt said: "We are encouraged by the strong performance delivered in the first quarter and remain on track to pilot our customer focused multi-channel proposition in three brands during the second quarter.
"Mindful of the political and economic uncertainty surrounding the EU referendum we are taking a cautious view of the coming months.
"Notwithstanding this, however, we continue to expect to make strong progress in 2016 as we execute our strategy and maximise market opportunities and therefore maintain our current financial outlook for the full year".