THE SNP's Westminster leader has said that Boris Johnson would pack his bags and follow his most senior advisers out the door "if he had a shred of integrity".

Ian Blackford lashed out after the announcement that Dominic Cummings has resigned his role in Downing Street with immediate effect.

The SNP MP said Johnson's time as Prime Minister had been characterised by "abysmal failure, utter incompetence, and the alienation of Scotland and the other devolved nations".

Blackford was speaking in the wake of Laura Kuenssberg announcing that Cummings and the Prime Minister had had a discussion and decided it was best for the special advisor to resign immediately, rather than waiting until the end of the year.

Kuenssberg has often had insights into Downing Street's inner workings which many have speculated could coming directly from Cummings.

Just yesterday, the BBC journalist tweeted that Cummings had told her that "rumours of [him] threatening to resign are invented".

Tweeting today, Kuenssberg wrote that the departure had been brought forward because of the "upset" in the Downing Street team after a "difficult week".

"This was all a slow burning fuse but exploded fast when it finally happened! End of a very torrid era," she added.

READ MORE: BBC's Laura Kuenssberg under fire for ‘false’ Scottish independence report

The now former special advisor to the Prime Minister was seen leaving No10 carrying boxes just a short time ago. However, reports say that Cummings will continue to work from home for Johnson until mid-December.

The special advisor's resignation comes a short time after the row over his fellow Vote Leave veteran, No10's former communications director Lee Cain.

Cain left Downing Street earlier this week after leaks suggested he was to be promoted to chief of staff, against the wishes of many inside No10, including the Prime Minister's partner Carrie Symonds. 

Cain had his last day in Johnson's team, and was reportedly present at the discussion between Cummings and the Prime Minister this afternoon.

Commenting, Blackford called for Johnson to follow his advisers out the door.

Blackford said: "Boris Johnson's most senior advisers are abandoning the Prime Minister like rats on a sinking ship – just as the UK faces a devastating extreme Brexit, a second wave of coronavirus, and a growing Tory unemployment crisis.

"It tells you everything you need to know about this arrogant, incompetent and self-serving Tory Government that they are ditching their responsibilities at the exact moment their reckless decisions are causing the maximum damage to people across the UK.

"If the Prime Minister had a shred of integrity he would pack his own bags and go with them.

"His tenure has been beset by abysmal failure, utter incompetence, and the alienation of Scotland and the other devolved nations."

Nigel Farage has said that Cummings's departure signals that "a Brexit sell-out is close".

READ MORE: Michael Gove pelted by angry doctors over defence of scandal-ridden vaccine chief

With the EU and UK still struggling to find common ground on key areas such as fishing, the level playing field, and state aid rules, a No-Deal Brexit come 2021 is looking increasingly likely.

It is unclear if Cummings's departure will herald a new, softer stance from the Tory Government he has often been accused of running. 

The Telegraph is reporting that Sajid Javid, the former chancellor who quit the role after clashing with Cummings over the sharing of aides, will become chief of staff.

Johnson has asked Edward Lister to take on the Downing Street position for an interim period, a position he formerly filled while Johnson was Mayor of London.

Michael Gove is also tipped to take the role of health secretary from Matt Hancock as part of a reshuffle ahead of 2021.