“Both require longer-term investments so liquidity may be a challenge, but that’s the kind of trade-off investors should be prepared to make.”

Illiquidity can, to an extent, be mitigated by the type of investment product used. Open-ended portfolios can be vulnerable to outflows if investors panic, as those running certain property funds learned in the wake of last year’s Brexit vote.

In the case of an investor exodus - or signs of one - fund providers can opt to take punitive measures against those looking to take their money out, as happened in 2016.

Investment trusts

Because of these considerations, some specialists instead favour investment trusts, which trade shares and are not directly exposed to the whims of fund flows.

“Investment companies are listed companies on the stock exchange so investors can always buy and sell shares freely,” says Ms Brodie-Smith.

“Investment company managers do not have to manage inflows and outflows and can take a long-term view of their portfolios, without being constrained by the illiquid nature of the asset class.”

Unfortunately for investors, this creates a problem already witnessed in other equities: high prices. Share prices have soared on many infrastructure vehicles, with these trading at significant premia to the value of the assets held.

As such, using infrastructure investment trusts may have become an issue of investment timing. For some, now is a time to stay away.

“Such has been the demand for the asset class and particularly income-generating trusts that most infrastructure investment trusts are trading on significant premiums.

It is for this reason that we are not investing in these vehicles at present,” says Gavin Haynes, of discretionary investment management firm Whitechurch Securities.

Investors may have to choose how, and when, they turn to infrastructure as an investment. But as with HICL, this may be a wise play for the longer term.

Dave Baxter is an investment writer for FT Specialist and news editor for Investment Adviser