Faced with such an unpredictable brew of economic and political forces, we should perhaps take a step back and remind ourselves of the original case for investing in Ceres: that it has world‑beating green energy technology and a business model. 

It is based on leaving manufacturing to partners, that offers the prospect of rapid growth in production all undertaken at someone else’s risk and funded by someone else’s capital.

We are however asking readers to take a lot on trust: that the technology will attract enough customers that Ceres’s partners will build fuel cells in sufficient quantities to offer a decent return, in the form of royalties, for its investment in its designs.

But the case is just as strong as when we first tipped the shares – or stronger still. We’ll hold on.

Questor says: hold

Ticker: CWR

Share price at close: 731p

Update: AJ Bell

If we bought a good business too expensively with Ceres Power, can we buy a good business cheaply with AJ Bell?

Admittedly the shares are 27pc higher than when we advised readers who took part in its flotation in December 2018 to bank a quick 50pc profit a month later. But the business is also a lot bigger and a lot more profitable.

“It may have been the right call to sell three years ago but since then the firm has reported three years of strong earnings growth – of 26pc, 28pc and 13pc,” says Eric Burns of Sanford DeLand Asset Management, whose Free Spirit fund recently invested in the stock. 

“The operational performance of the business has gone gangbusters – this is a company that has grown very strongly over the past two years without the share price keeping up.”

Some investors worry that investment platforms’ profits are too tied to the performance of the stock market as a whole. 

AJ Bell’s headline charge, for example, is 0.25pc a year of a customer’s assets. If the stock market crashes, so too will that customer’s wealth and AJ Bell’s cut of it. But Burns says there is more to the story.

“Rising interest rates are good for platforms because they mean more interest on customers’ cash deposits. A rise of a quarter of a percentage point in interest rates would offset a 10pc fall in the markets, for example,” he says.

“And while it is anyone’s guess what markets will do in the short term, our holding is not predicated on markets having another good year; it’s more a structural story over the next five to 10 years. 

This is an ably run and respected business and one that treats its customers well.” Time to buy.

Questor says: buy

Ticker: AJB

Share price at close: 305.2p

Read the latest Questor column on telegraph.co.uk every Sunday, Tuesday, Wednesday, Thursday and Friday from 5am.

Read Questor’s rules of investment before you follow our tips.