City Eye: Alimentary, my dear Watson: the proof of our population

I've always taken pride in my richly merited obscurity but last week's column, with its alimentary metric (we are numbered by what we eat and the best guess for the UK population is 77 to 80million) rattled the cages of many readers and those of a couple of TV producers. Despite my efforts, no one is yet brave – or should that be foolish? – enough to come on the record and stand behind their estimates.

It's frustrating that the supermarkets should be daylight agnostics – brave in front of the Competition Commission but pusillanimous when asked to air their views on the real size of the population outside a closed hearing.

As promised last week, I'll ventilate some of the arguments around this alleged secret surge in population and how this will lift house prices. But first let me clarify the logic of alimentary metric. Many readers seemed to assume I was suggesting that retailers and the agricultural industry were basing their estimates of population, or market size, on some sort of straight-line correlation between sales and population. No, no, no.

The reality is that supermarkets, in particular, have a sophisticated understanding of their market. But it's not such a quantitative analysis; there is a real qualitative understanding of our patterns of consumption (appe- tite disorders, gluttons, simple waste, the food sub-sectors that absorb excess cash; Veuve Clicquot consumption is not a great indicator of number, but a decent metric of affluence).

It is, for example, a statistical fact that beer sells better if positioned on the shelves next to babies' nappies. The merchandising logic is simple: many hard-pressed young parents feel they are entitled to a little treat after the last nappy change of the day.

I'm sorry there wasn't space last week to include analysis of these basic variables. Compression led some readers to believe that the retailers, or I, had missed these things. Not the case.

One thing is certain, though: we have a shortage of housing in the UK and the problem is getting worse. Iain Sim spent three decades in the public sector before heading up a quasi-private housing association in the North- east. Coast and Country Housing has over 10,000 properties on its books, worth some £1.4bn. Mr Sim says we don't have enough houses now, that new builds are way behind the level of demand, and that Gordon Brown, while addressing the problem, is dealing with the matter late in the day.

Mr Sim is rolling out his stock into private ownership, but just cannot get his hands on enough property.

Bog standard

Many thanks to David Walker, a reader, who suggests an alternative metric for population: loo paper. "A ton of toilet rolls is bought and consumed by X number of people per year and this will stay fairly constant," he writes. Worth looking into.

martin@martinfdbaker.com