Thanks to everyone for their contributions. It's been a really good read.
Asset allocation is always interesting. More often than not, the ideal portfolio is only known through hindsight. It’s retrospective view on what we should have done. It cannot with any degree of confidence predict what will happen. Just look at all the predictions from the fund houses and banks for 2025. Some common themes but lots of variance. Logic and investing don’t tend to be common bedfellows.
So what to do?
One option (back to the beginning) is to choose a diverse multi-asset fund (two or three if provider risk is a concern) and simply let time do it’s thing. But none are the same. You need to choose between hedged / unhedged bonds or inclusion of home bias, property, junk bonds, linkers, gold, and so on.
Another option is to choose your own individual asset allocations based on Swenson, Hale, Harry Browne, Jack Bogle, or similar portfolios. Takes a little more effort. Interestingly, the Slow and Steady portfolio created by Monevator in 2011 has performed exactly the same as a LifeStrategy '70'. I think it started out as 80% equity but dropped to 60% equity. All that work (and fun) to end up somewhere in the middle.

Other options include ITs with a long track record, discounted opportunities, thematics, valuations, buy and hold, assets that cover all bases, 100% equity, you name it.
What I do feel each private investor
must do is think about maximum portfolio loss that would be tolerable. One line of thinking is to limit an equity allocation to twice that figure (based on a 50% market drop). So if you can only stomach a 20% loss then it’s a 40% equity allocation. Great theory, but when bonds started their reset to normality in 2022, I wonder how many PIs thought they could possibly 'lose' 20% from their bond allocation?
There is no right or wrong. It is clearly possible to outperform the market. But I wonder how PIs fail to do so and end up underperforming. A multi-asset fund might just stop that unnecessary 'self-destruct' button.