The relationship between the Prime Minister and Chancellor is an integral part of any Government.
When it works, they look powerful. When it doesn't, the government can look dysfunctional.
Reports emerged earlier this week of a rift between Mr Javid and the prime minister's chief adviser, Dominic Cummings.
Mr Javid downplayed the rumours, saying people shouldn't believe everything they read.
But Mr Javid's resignation as Chancellor due to his reluctance to sack his political advisers has raised the question - has Number 10 now got too much power?
Until now the Chancellor has had his own team of special advisers as well as the vast Treasury apparatus at his disposal.
This is now being replaced with an integrated Number 10-Treasury team of advisers at the top of that structure.
In theory they will report to both the new Chancellor and the Prime Minister. In effect the Prime Minister and his chief advisor Dominic Cummings will ultimately be in charge.
Dominic Cummings appears to have won his battle with the former Chancellor - will Rishi Sunak or anyone now be able to challenge the Prime Minister?