Boris Johnson has said that referendums should only be held “once in a generation”.

He told the BBC’s Andrew Marr programme: “Referendums in my experience, direct experience, in this country are not particularly jolly events.

“They don’t have a notably unifying force in the national mood, they should be only once in a generation.”

Asked what the difference was between a referendum on EU membership being granted and another on Scottish independence being requested following the 2014 vote, he said: “The difference is we had a referendum in 1975 and we then had another one in 2016.

“That seems to be about the right sort of gap.”

READ MORE: Iain Macwhirter: Can Nicola Sturgeon finally deliver an independence referendum in 2021?

On the matter of Brexit, Johnson claimed that “substantial sums of money” are coming back to the UK due to Brexit saying “For instance, they’ve already got substantial sums of money coming back into this country as a result of leaving the EU.

“We’ve got control over our borders, a points-based immigration system has already been established.

“And then when it comes to areas in parts of the country that feel that they’ve been left behind, one of the things that you can do for instance, to say nothing more (of) the regulatory changes you can make, one of the things you can do is have free ports.”

He added: “You can use tax systems and subsidies in order to drive investment.”

The PM also gave an update on the UK's vaccination program saying he expected “tens of millions” of vaccine jabs to be administered over the next three months.

Mr Johnson said: “I wish I could give you here and now any sort of elaboration on the figures you have already heard about how we hope to get up to two million a week and so on.

“I can’t give you that yet.

“What I can tell you is that… we do hope that we will be able to do tens of millions in the course of the next three months.”

He added there will be 530,000 doses of the Oxford/AstraZeneca vaccine at around 540 GP vaccination sites and around 101 hospital sites on Monday, “on top of the million or so that have already been vaccinated”.

He said: “There are a few millions more Pfizer (vaccines) still to be used.”  

READ MORE: The war over scallops and the future of sustainable fishing in Scotland

“We are rolling them out as fast as we can. And the issue is not so much one of distribution, and I saw some of your earlier guests sort of saying ‘well you know we haven’t got enough retired doctors to help administer (them)’.”

He also hinted that Covid restrictions in England were likely to get tougher saying: “What we are doing now is using the tiering system, which is a very tough system… and, alas, probably about to get tougher to keep things under control.

“But, we will review it.”

He added: “And we have the prospect of vaccines coming down the track in their tens of millions.

“And that, I think, is something that should keep people going in what I predicted, back on your show in October, will be a very bumpy period right now.

“It is bumpy and it’s going to be bumpy.”

Addressing school parents in England, Johnson said he has “no doubt” that schools are safe and parents should send primary-age children back to classrooms this week where schools remain open.