> A yard is nearly a metre so that survives too and is conveniently made up of three feet and they are around 30cm, which is a short ruler. An inch is 2 1/2 cm and is roughly the size of your thumb to the first joint. The pound is a small half kilo

I think a lot of people who have attachment to non-metric units, their attachment is more to the names (and in some cases the interrelationships) rather than the precise values. I wonder why more consideration wasn't given to metrication by redefinition:

1 metric inch = 25.0 mm exactly (0.4 mm shorter than the old inch)

1 metric foot = 30 cm exactly (4.8 mm shorter than the old foot)

1 metric yard = either 90 cm exactly (1.44 cm shorter than old yard) or 1 metre exactly (8.56 cm longer)

1 metric mile = either 1.5 km exactly (609 m shorter than the old mile) or 1.6 km exactly (9 m shorter than the old mile) (either way, with 1 metre = 1 metric yard, 1 mile would be either 1500 or 1600 yards, which is easier to remember than 1760)

1 metric pound = 500 grams (46.41 g heavier than the old pound)

1 metric ounce = either 30 grams (so a metric pound is actually 16⅔ metric ounces–1.65 grams heavier than the old ounce) or 31.25 grams (so a metric pound is exactly 16 metric ounces–2.95 grams heavier) or 25 grams (20 metric ounces to a metric pound, 3.35 grams lighter than the old metric pound)

I know some people would get confused by old versus metric, but people already have to deal with some of that already (e.g. troy ounces vs avoirdupois ounces, short vs long ton, UK vs US gallon, statute miles vs nautical miles, etc). Actually some European countries did pursue this approach seriously – both France and Germany redefined the "pound" as 500g in the 19th century, and in both countries it still sees some use in informal contexts. But in the English speaking world, it was considered, but for whatever reason never seriously pursued.

> I'd love to see you pour a pint to five decimal places!

I wonder why the UK doesn't follow (most of) Australia's example and redefine the pint (for the purposes of draught beer only) as 570 mL?

> I note you mention schooners and the like in AUS (and why on earth do you have a different pint size - it doesn't really matter) and that basically proves my point about routine odd units still in use, everywhere.

People don't really think of standardised beer glass sizes as units of measure. Nobody would try to measure anything (except the quantity of beer they've drunk) in schooners, unless they were indulging in a colourful metaphor. Traditionally Australia has this complicated system of 6-7 different beer glass sizes, which is somewhat different in each state – originally they were all defined in terms imperial fluid ounces, and then with metrication they were rounded off to the nearest 5mL – but in practice most places only have two of them on offer, occasionally a third. So a "pint" in Australia is really no more a unit of measure than a "schooner" or "middy" or "pot" is. A few places (generally German/Austrian themed bars/restaurants) also sell draught beer by the stein (1 litre) or half-stein (500 mL). Unlike the UK, in Australia you can legally sell draught beer in whatever sized glass you wish, so long as it isn't likely to deceive customers.