Financial services regulation will also receive a shake-up, with new objectives for the Prudential Regulation Authority (PRA) and Financial Conduct Authority (FCA) to unlock growth.
There will also be a series of smaller announcements, including on investment in science and technology.
Taken together, the Chancellor will claim these policy changes will amount to one of the biggest upheavals of the industry in a generation.
After months of deliberation, Reeves has concluded that big is beautiful when it comes to pensions, inspired by a trip to Canada this summer and keen to build on plans initially laid out by the Treasury under Jeremy Hunt, her predecessor.
It is understood her speech will address how Canada’s pension schemes invest around four times more in infrastructure than here in the UK, while Australian pension schemes invest around 10 times more in private equity compared to Britain’s workplace funds.
A raft of consultations on exactly how this will be done will be launched in the wake of her speech.
However, one main point of contention is exactly how the Chancellor will entice pension funds to buy British, particularly given how much cash has been ploughed into overseas assets in recent years.
For some observers, including two former pensions ministers, the solution lies in forcing funds to do so.
Baroness Altmann wants to see “at least 25pc of new contributions invested in domestic assets if pension funds want the tax relief”.
She highlights how pension relief costs taxpayers more than £70bn a year, indicating that the Government should demand more domestic investment in return.
“In exchange for these generous tax subsidies, there is clearly justification for the Government to require more pension assets to support UK markets, infrastructure and economic growth,” she says.
Guy Opperman, another former pensions minister, agrees: “For years, the UK taxpayer has subsidised private sector pension funds and private individuals to get a better outcome for their pensions. It is now time that the UK pension funds returned the compliment and invested back in the UK.”
However, others are dead set against the idea.
The Universities Superannuation Scheme (USS), the UK’s largest private pension fund, has warned that such a move would be “wholly inconsistent” with trustees’ duties to provide the best outcomes for pension savers.
Andrew Bailey, the Governor of the Bank of England, has also said he would not “for a moment” support the idea of forcibly making pension funds back British companies, even as he conceded that policymakers had “a lot of work to do” to improve outcomes for savers.
He is joined by the International Monetary Fund (IMF), which has warned that the UK’s move towards investing in private assets could trigger a sudden withdrawal of pension funds, raising the risk of a Woodford-style collapse in the sector.
The IMF said this could quickly spiral into a bond market meltdown, dragging down stock prices and triggering a dangerous chain reaction.
All this leaves the Chancellor with food for thought. And while her speech will unveil the most radical reform for pension investment in decades, some in the room could end the night muttering into their sherries that she has not been bold enough with her plans.
That’s because the elephant in the room at Mansion House will not be the local taxpayer-backed LGPS, but the growing pool of money in Britain’s biggest corporate pension schemes.
There are thousands of shuttered defined-benefit (DB) pension schemes across companies up and down the country, from the likes of Marks & Spencer to family-run minnows.
Many of these schemes, which in total have £1.5 trillion in assets, are now in increasingly rude health.