Jim Armitage: Investors need Mark Carney to find Janet Yellen's consistency on interest rates

If Mark Carney is the unreliable boyfriend, Janet Yellen is the faithful bride.

Whereas the Bank of England Governor earned his dodgy nickname for flipping his guidance about when he’ll be increasing interest rates, the Fed boss has done the opposite.

She’s never strayed from her line that US rates would rise by the end of the year.

Last night, by a unanimous vote of the US central bank, she made good on her pledge.

The response? Despite the gamble of ditching a seven-year stretch of free money, the markets glowed.

The love affair between the Fed and finance has never been stronger.

Yellen has heeded the lessons of her predecessor’s relationship failure. In 2013, Ben Bernanke suddenly declared he was planning on tapering off QE — the shock equivalent of the normally doting boyfriend staggering home at 2am with a brace of Latvian strippers.

The markets went berserk: “taper tantrum!” shouted the headlines.

Unlike the Fed, Carney hasn’t quite learned the error of his inconsistent ways.

Although he’s dropped the guff two years ago about raising rates when unemployment fell under 7% (it’s now 5.2% and still no move), the Bank still has a tendency to stray, with hints at rate rises subsequently denied as personal opinions.

“You don’t want to know everything that’s going on in my mind, I can assure you,” he joked to the FT yesterday.

But we do, Mark, as we try to work out if we can afford the mortgage.

If this relationship of ours is to work, you have to learn from Yellen and communicate.