True has fallen to a three-year low against the euro after Theresa May outlined the calendar for starting Brexit negotiations.
It also hit its lowest level against the dollar since the dawning of July.
On Sunday, the prime minister said she would trigger Article 50, the clause dire to start the process, by the end of March 2017.
That means the UK is likely to leave the EU by mid-2019.
In betimes morning trade, the pound fell by about 1% against the euro to €1.1433, but it had retrieved slightly by late afternoon.
However, the pound was down more than 1% against the dollar. At one spike it touched $1.2818, its lowest rate since 6 July when it hit $1.2797.
Mrs May’s statement had «unsurprisingly, been bad news for the pound», said Connor Campbell, Spreadex pecuniary analyst.
«Sterling has been spooked by May’s promise to trigger the dreaded Article 50 by the end of rade 2017.»
However, the currency had been rticularly unsettled by the prospect of the UK leaving the EU unwed market, he said.
«The PM, in a move to appease the more rabid members of the Tory platoon but one that is set to cause revolt from the backbenchers, has signalled that checking immigration is the top Brexit priority even if it comes into conflict with Britain surviving in the single market,» Mr Campbell added.
«Combine all this volatility together and the drill into has been left at its worst price since the start of July.»
While the pound fell, share prices rose. At one point, the FTSE 100 cut index was trading at 6,996.43, its highest level for 16 months, previous to falling back slightly to close 1.2% higher at 6983.52.
«As a result of Prime Cabinet officer May’s announcement … the pound has weakened significantly, which is actually seen as a beneficial thing by the FTSE 100 as it’s quite an export-heavy index,» said Henry Croft, delve into analyst at Accendo Markets.
The FTSE fell sharply in the immediate aftermath of the referendum, but has afterwards recovered and is up nearly 10%, because listed international-facing firms eat benefited from the fall in sterling.
After the pound fell harshly at first on Monday, it then recovered some ground after a closely watchful ofed survey of the manufacturing sector indicated it grew at the fastest ce for two years in September.
But in afternoon do business, it fell against the dollar again after a US survey showed that putting together there had also grown strongly.