BORIS Johnson has pledged that a new test and trace system, seen as the key to easing the lockdown south of the Border, will be up and running by June 1, just 12 days away.

But the Prime Minister said the rollout of the contact tracing mobile phone app would come later.

At Question-Time in the Commons, Mr Johnson said 25,000 staff would be in place by the start of next month and they would be capable of tracking the contacts of up to 10,000 new Covid-19 cases a day.

The June 1 date is important as it is the earliest possible date earmarked for the gradual reopening of schools and shops in England.

In Scotland, a contact tracing system is to be trialled from next week in three health boards: NHS Fife, Lanarkshire and Highland.

The Scottish Government has chosen a system of alerting people by a telephone call rather than the mobile phone app being trialled south of the Border but it has not ruled out adopting such technology in the future.

The PM’s June 1 pledge came after his Cabinet colleague Robert Buckland conceded there might not be a "uniform approach" to reopening England's schools in the face of stiff opposition from some councils and trade unions.

Professor Dame Angela McLean, the Government's Deputy Chief Scientific Adviser, has said the modelling for changes to the lockdown were based on a "highly effective track, trace and isolate system" being in place.

At PMQs, Mr Johnson said: "We're making fast progress in testing and tracing and I have great confidence that by June 1 we will have a system that will enable us, that will help us very greatly to defeat this disease and move the country forward."

The capacity to trace the contacts of 10,000 people far exceeds current levels of confirmed Covid-19 cases.

At the daily Downing St press conference, it was announced that across the UK there had been 35,704 deaths from Covid-19, a rise of 363.

However, Public Health England testing data from yesterday showed not a single coronavirus case was diagnosed in London or South East England from swabs taken on Monday.

The PM has pledged to have a capacity to do 200,000 tests by the end of the month. Oliver Dowden, the Culture Secretary, at the No 10 briefing announced there had been, in the 24-hour period up to 9am on Wednesday, 177,216 tests - carried out or dispatched.

Widespread contact tracing was abandoned in mid-March as the number of cases soared in the UK.

Last week, Matt Hancock, the UK Government Health Secretary, said the contact tracing app would be rolled out across England from mid-May but it has now been pushed back.

During PMQs, Mr Johnson did not mention the app, currently being piloted on the Isle of Wight, as part of his plan for June 1.

Downing Street later confirmed that the app would be rolled out "in the coming weeks" after the introduction of human contact tracing.

The PM’s spokesman told a Westminster briefing the app was “only one part of the system" and that there was already a "tried and tested" system for tracing and testing people.

Asked earlier if the reopening of schools in England depended on test, track and trace being fully in place, Mr Buckland said: “The position is somewhat more nuanced than that."

UK ministers are facing pressure from several councils and teaching unions to reconsider plans to reopen English primary schools.

At the moment, Reception, Year 1 and Year 6 are due to go back from June 1 at the earliest, with other years phased in before the summer break.

Mr Buckland insisted the Government was taking all concerns "very seriously".

He told the BBC: "I don't think any of us want to put either children or our dedicated teaching staff in any danger at all, and the question of being safe is clearly paramount.

"So we're all working towards June 1 and planning for that return, but I accept the point that there may well be issues from employers that need to be addressed which might not mean we'll see a uniform approach on June 1."