The Foreign Secretary has modelled herself on Mrs Thatcher, her political hero, most recently being pictured riding in a tank 35 years after the former prime minister posed for a similar photograph.

Allies of Ms Truss said she was keen to get off to a quick start in her new role and would reopen formal talks over the protocol, which has led to trade frictions between Northern Ireland and the rest of the UK, in the new year.

Alongside her deputy Chris Heaton-Harris, the newly appointed Europe minister, she wants to maintain the hard-nosed approach to negotiations adopted by Lord Frost, who last week resigned because of concerns over the Government’s direction.

‘Protocol negotiations are in safe hands with Liz’

“Protocol negotiations are in safe hands with Liz – she’ll do a great job,” a source told The Telegraph. “Her outlook and ideology are similar to Lord Frost, so don’t expect any radical early changes in approach, although she’ll of course do it her way.

“Liz is a really tough negotiator, knows trade inside out and will fight hard for Britain and not roll over.”

She will push for a Swiss-style arbitration system that would remove the EU’s ability to immediately escalate disputes to the ECJ.

If applied to the protocol, a panel would first attempt to resolve disputes over issues such as food safety before European judges are given a say on matters of EU law as it is applied in Northern Ireland.

Under the current system, the EU can essentially bring the UK before its judges if it fails to implement the bloc’s laws properly in the province.

The threat to trigger Article 16, which would unilaterally suspend parts of the Brexit treaty, remains on the table if a solution is not reached in the coming months. Talks are expected to continue for up to two months into next year, with sources suggesting the end of February is now the cut-off point for an agreement.

Industry leaders and academics in Northern Ireland have said they hoped Ms Truss’s appointment would lead to a deal.

“Given Truss’s focus as International Trade Secretary and as Foreign Secretary has been getting deals and building bridges, I think there is hope for renewed momentum in the UK-EU talks over the Protocol in the new year,” Prof Katy Hayward, of Queen’s University Belfast, said.

Stephen Kelly, of Manufacturing NI, said: “Perhaps this is a chance for a change of tone and negotiating approach which is more likely to lead to the success which firms and families need.”