The mood in markets was lifted by stronger-than-expected Chinese factory output and news that Moderna Inc said its experimental vaccine was 94.5% effective.
Broadly speaking, the risk-positive aspect of major markets is still there and I think that's going to help to support sterling.
Euro zone shares fell and London's FTSE 100 dropped to its lowest level in six months. The dollar index rose around half a percent as investors sought safety.
The EU's chief negotiator, Michel Barnier, is in London for negotiations, after which the talks will continue in Brussels.
The dollar strengthened, equities fell, and markets were broadly risk-off. Analysts cited new lockdowns in Europe and record-high daily virus cases in the United States.
Right now there's a bit of optimism creeping in from the weekend developments - the extension of the talks until Wednesday,
Sterling's implied volatility gauges soared to a seven-month high of more than 13pc indicating investors were prepared for unexpected moves in the British currency in the next hours.
The pound gained 0.3pc in early trading to touch $1.3006, the first time it had broken the mark since mid-September, before giving up its gains. It was last down 0.1pc at $1.2962.
Johnson does not want the Brexit transition to end without a new trade deal in place, he said on Sunday, but he believes Britain could live with such an outcome.
Significant issues remain between Britain and the EU Union about their post-Brexit trade relationship, British housing minister Robert Jenrick said on Friday.
The EU on Thursday launched a legal case against Britain over its new Internal Market Bill that undercuts London's earlier legal commitments under its Brexit divorce treaty.
Sunak, who announced on Wednesday that he would not now set out a full budget later this year, was expected to unveil a lifeline to some furloughed workers in a speech around 1045 GMT.
Sterling recovered as much as 0.08pc to $1.2826 against the dollar at 0840 GMT, after sliding as low as 1.2714 earlier on Tuesday, its lowest since July 23.