Sterling shot higher against the euro and dollar on Wednesday, with traders citing options expiries and some positive expectations for Prime Minister Theresa May's weekend meeting with US President Donald Trump.

Before then, there are nerves over the strength of fourth quarter gross domestic numbers due on Thursday, but more clarity about the planned launch of Brexit talks in March have seen sterling recover to its strongest since mid-December.

A burst of morning buying, running parallel to gains for the euro against the US dollar, drove the pound to a six-week high of $US1.26 ($1.67). It gained as much as 0.4 per cent to 85.30 pence per euro, an almost three-week high.

"There have been people chasing options expiries and some stop losses this morning, but there are also a number of people talking about the chances of some positive news for the UK this weekend," said a trader with one international bank in London.

"It seems like there is a reasonable chance we may see a strong headline on US-UK trade at some stage."

May is due to meet Trump on Friday.

The pound took a rollercoaster ride on Tuesday after a Supreme Court ruling that Britain's government must go through parliament before starting talks to quit the EU and analysts continue to consider the political fallout.

One question is how politicians in Northern Ireland and Scotland will proceed in the weeks ahead after the court also ruled the government does not need to go through the UK's regional assemblies to start Brexit talks.

The government will move to lodge the legislation necessary to launch the talks within days but opposition parties are expected to seek to amend it.

"The big moves in sterling came yesterday and now it is a case of pausing for breath," said Societe Generale currency analyst Alvin Tan.

"What happens in parliament will now be important as there appears to be a push for the government to publish a white paper on its Brexit plans."