The Prime Minister says delivering Brexit is the best way to answer those calling for independence for Wales and the best way to secure Wales' place in the United Kingdom.
In an interview with me at the Conservative party conference in Manchester, Boris Johnson also:
Talks of big opportunities for sheep farmers to sell Welsh lamb to the United States after Britain leaves the EU
Rejects calls for more devolution, saying that Wales 'already has considerable powers...and the results aren't brilliant'
Rejects calls for a wider role for Welsh Tory leader saying there's 'no change' in the status of the position
Says he'll study the impeachment plan from his 'good old friend Adam Price ... with lively interest.'
Future of the United Kingdom
Recent polls and well-attended protests have suggested that support for independence in Wales is increasing.
Backers of Wales remaining in the United Kingdom have warned the Prime Minister's Brexit stance is fuelling that increase.
He rejected my suggestion that his approach is risking the break of up of the union he is supposed to protect. He insisted that delivering Brexit and showing the potential opportunities was the answer to those concerns.
More powers for Wales?
Some think the way to head off calls for independence is to give Wales more say over its own affairs, more devolution of powers over things such as policing or the benefits system.
What the Prime Minister had to say will disappoint them.
No change for Welsh Tory leader
There are many more important things to worry about, I realise, than the status of the Welsh Conservative leader. The reason I keep asking Prime Ministers about it is because I know it matters to senior Welsh Tories.
In 2012 David Cameron told me he considered the then leader Andrew RT Davies to be the leader of the wider Welsh Conservative party. Theresa May took a different tack and referred to both Andrew Davies and his successor Paul Davies as the leader of the Welsh Conservative group in the Assembly.
The Welsh leader is chosen by members in Wales, the only senior figure in the party here to be directly elected and many Tories have pointed to the ambiguity as problem for the party.
Boris Johnson would only say that 'there is no current change in the situation' and that 'it's been a subject of some discussion.'
Paul Davies himself has spoken publicly about the need to clear up the confusion and establish once and for all that his role is, indeed, to lead the Welsh Conservatives.
I asked him if he were disappointed by what the Prime Minister told me.
Plaid Cymru is trying to persuade the other opposition parties in the Commons to back its plan to impeach Boris Johnson for his unlawful prorogation of parliament.
When Plaid politicians talk about the process, they gleefully point out that Boris Johnson support the last attempt to impeach a Prime Minister. He was a backbench MP when Adam Price, then an MP, now Plaid's leader, made the attempt.
I wouldn't expect Boris Johnson to agree with the attempt to impeach him although he said he knew nothing about it and that I was breaking news to him. But I did wonder if he still backs the principle behind it. All he would say is that he would study what his 'good old friend Adam Price' is suggesting 'with lively interest.'
You'll be able to see some of my interview in Wales at Six and a fuller version on Sharp End at 10:45pm.