Reeves has welcome support from Bank's governor as she goes for growth and seeks to woo City
When Gordon Brown delivered his first Mansion House speech as chancellor he caused a stir by doing so in a lounge suit, rather than the white tie and tails demanded by convention.
Some 27 years later Rachel Reeves is the first chancellor who would have not drawn a second glance had they addressed the City establishment in a dress.
As the first woman in the 800-year history of her office, Ms Reeves's tenure will be littered with reminders of her significance, but few will be as symbolic as a dinner that is a fixture of the financial calendar.
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Her host at Mansion House, asset manager Alastair King, is the 694th man out of 696 Lord Mayors of London. The other guest speaker, Bank of England governor Andrew Bailey, leads an institution that is yet to be entrusted to a woman.
Ms Reeves's speech indicates she wants to lean away from convention in policy as well as in person.
By committing to tilting financial regulation in favour of growth rather than risk aversion, she is going against the grain of the post-financial crash environment.
"This sector is the crown jewel in our economy," she told her audience - many of whom will have been central players in the 2007-08 collapse.
Sending a message that they will be less tightly bound in future is not natural territory for a Labour chancellor.
Her motivation may be more practical than political. A tax-and-spend budget that hit business harder than forewarned has put her economic program on notice and she badly needs the growth elements to deliver.
Her plans to consolidate local authority pension schemes so they might match the investing power of their Canadian and Australian counterparts is part of the same theme.
Infrastructure investment is central to Reeves's plan and these steps, universally welcomed, could unlock the private sector funding required to make it happen.
Bank governor frank on Brexit and growth
If the jury is out in a business financial community absorbing £25bn in tax rises, she has welcome support from Mr Bailey.
He is delivered some home truths about the economic inheritance in plainer language than central bankers sometimes manage.
Britain's growth potential, he says, "is not a good story". He describes the labour market as "running against us" in the face of an ageing population.
With investment levels "particularly weak by G7 standards", he thanked the chancellor for the pension reforms intended to unlock capital investment.
He is frank about Brexit too, more so than the chancellor has dared.
While studiously offering no view on the central issue, Mr Bailey says leaving the EU had slowed the UK's potential for growth, and that the government should "welcome opportunities to rebuild relations".
There is a more coded warning too about the risks of protectionism, which is perhaps more likely with Donald Trump in the White House.
"Amid threats to economic security, let's please remember the importance of openness," the Bank governor said.
All that is welcome for Ms Reeves.
Already a groundbreaking chancellor, she is aiming for a political and economic legacy that extends beyond her gender and the dress code.