A bit later in the interview McDonnell says that Labour isn't interested in forming a coalition government in the event of another hung Parliament and would 'govern' as a minority administration. This is a daft statement, as we know minority administrations cannot 'govern' effectively, which is why a general election is imminent now that Boris has no majority. In reality McDonnell and Corbyn would be on the blower to Sturgeon within hours, if not minutes, of a hung Parliament.
In discussing how Labour would reverse the Leave mandate, McDonnell comes out with possibly the most deluded statement of the entire interview: "I've never seen the Parliamentary Labour Party more united than it is at the moment". He says this with a straight face. The PLP is so divided that it's not so much a case of which of the other opposition parties would back Corbyn as a 'caretaker PM', but how many of his own MPs would. Remember that when it came to a vote of no confidence in him in 2016, they voted overwhelmingly against him 172-40. However, during this interview McDonnell refuses to countenance a defeat for Corbyn if it came to forming a caretaker government.
There was an awkward question about what McDonnell refers to as the 'armed struggle', as if Campbell was looking for a damaging soundbite. However, the Ra man dodges the question. This is a fascinating interview and insight into the mind of a Marxist and somewhat surprising (or unsettling) to see the banter and frivolity between two men who have been at political loggerheads for years. Just don't mention Tories though...