Sterling extended earlier losses to hit two-month lows against the dollar and three-week lows versus the euro on Wednesday after data showing unexpected weakness in British retail sales and economic growth.
The Confederation of British Industry's distributive trades survey gave a balance of -24 in September, well below the forecast -15 and the fastest annual pace of fall in sales volumes for 22 years.
Final British GDP data for the second quarter showed annual growth at its weakest rate in 12 years at 1.5 percent, compared with a previous reading of 1.8 percent.
"The data has very much been the focus for the market today with GDP and CBI. The CBI survey was much weaker than expected and that is going to boost expectations that the Bank of England will cut interest rates again," AIB Group economist Geraldine Concagh said, adding there was a risk of another 25 basis point cut before the end of this year.
Sterling fell as far as $1.7619 by 1422 GMT, its worst performance since late July and a quarter percent loss on the day.
Sterling was also down a quarter percent against the euro, close to earlier three-week lows of 68.19 pence. Sterling was also quoted at seven-week lows on its trade-weighted index at 99.7.
On a more positive note for sterling, further data on Wednesday showed Britain's current account deficit narrowed by more than expected in the second quarter, to 3.05 billion pounds.
Sterling has been sensitive in recent weeks to any data seen increasing the likelihood of further Bank of England rate cuts, following a quarter-point cut in August to 4.5 percent.