Dominic Cummings became something of a household name last year, but not necessarily for the right reasons. 

The Barnard Castle extravaganza was a defining moment of the first lockdown, and caused outrage up and down the country.

He may have left his role as advisor to Boris Johnson at the end of 2020, but even then people felt fairly confident we had not seen the last of Cummings. 

And right they were; over the past few months, he has made a storming return to the public eye as he drops bombshell after bombshell on the Prime Minister he used to advise. 

The man behind Brexit's now defining "take back control" slogan certainly doesn't do things by halves, as demonstrated by his lengthy blog posts and extensive Twitter threads. 

Once at the heart of Government, some called him the most powerful unelected official. 

It hasn't boded well for those he has so far chosen to dish the dirt on - Cummings was scathing of former health secretary Matt Hancock who left his role last month after his affair with an aide was exposed by the Sun.

Now, in his first official interview since leaving Whitehall, he continues along this 'tell all' track, offering the BBC's Laura Kuenssberg an insight into what really goes on inside the number 10 offices.

The real question is will it damage Boris Johnson's position as Prime Minister? 

Here are five things we know ahead of the interview...

1. Johnson rejected an autumn lockdown in England because he thought it was only over-80s dying

According to Cummings, Boris Johnson went against scientific advice to introduce an autumn lockdown in England because people dying from Covid were "essentially all over 80", in the Prime Minister's words. 

The autumn spike of the virus led to thousands of deaths and eventually forced ministers to introduce an England wide lockdown in November.

Johnson's former aide told Kuenssberg that chief scientific advisor Sir Patrick Vallance and England's chief medical officer Professor Chris Whitty had pushed for tougher restrictions to be introduced in September, to which the Prime Minister allegedly responded: "No, no no, no, no, I'm not doing it."

Instead, Cummings said Johnson wanted to allow Covid to "wash through the country" to avoid damaging the economy. 

2. The Prime Minister "didn't buy all the NHS overwhelmed stuff"

It seems that Cummings' phone is filled with messages that could come back to haunt the Prime Minister; one deeming former Health Secretary Matt Hancock as "utterly useless" already surfaced earlier this year.

Johnson may now be rethinking what he writes on the app, with Cummings claiming that the Prime Minister had sent him a message saying he "didn't buy all the NHS overwhelmed stuff". 

Johnson repeatedly stood up at press briefings and thanked NHS staff and essential workers for their work on the frontline during the pandemic. 

However, according to Cummings, the Prime Minister did not believe the health service was in danger of being overwhelmed, despite evidence provided by NHS bosses and pleas from staff.

3. Boris Johnson supposedly refers to the Daily Telegraph as his "real boss"

A former journalist, Johnson was once editor of The Spectator and wrote a weekly column for the Daily Telegraph. 

Now Cummings alleges that the Tory leader and current Prime Minister "always referred" to the Daily Telegraph as "my real boss". 

A traditionally right-wing paper, the Daily Telegraph has printed some lockdown sceptic columns throughout the pandemic which have drawn widespread criticism.

The paper was even ordered to issue a correction after an article by columnist Toby Young suggesting London was close to herd immunity was deemed "significantly misleading" by Independent Press Standards Organisation (Ipso).

4. Boris Johnson wanted to continue face to face meetings with the Queen

Traditionally, the Queen meets the Prime Minister once a week for a face to face audience where they discuss what is going on in Government and around the country. 

These usually take place at Buckingham Palace, with only the Queen, the Prime Minister and occassionally the Queen's corgis present. 

Cummings claimed that the Prime Minister wanted to continue with these meetings at the beginning of the pandemic, with Cummings forced to talk him down. 

He told the BBC that on March 18 2020, Johnson said: "I'm going to see the Queen... That's what I do every Wednesday. Sod this. I'm going to go and see her."

In response, Cummings claimed he told the Prime Minister the notion was "completely insane" because people in the office were isolating and that either of them might have Covid. 

He alleges he told Johnson: "You can't go and see the Queen. What if you go and see her and give the Queen coronavirus? You obviously can't go.

"I just said, 'If you give her coronavirus and she dies, what are you going to [do]? You can't do that. You can't risk that. That's completely insane.'"

The Prime Minister eventually backed down and did not visit the Queen on this date. 

Number 10 has denied this exchange took place.

5. "Many many" people will back up Cummings' claims under oath

The former number 10 advisor has said that "many many" people would say "under oath to the public inquiry" that the claims Cummings has made are true. 

When challenged that the accusations were very strong, Cummings responded: "Yes, but lots of people were in the room and saw the same as what I saw. 

"That's why I've argued so strongly for, why I think MPs should take matters into their own hands and insist on an inquiry into all this now."

When will the interview air? 

The interview will air on Tuesday July 20 at 7pm on BBC 2, as well as being available on BBC iPlayer and BBC Sounds.