Softers) Uniformity of units is not necessary except to the tidy-minded. All you need to know is what you're getting and for all users to be familiar with those units. A pub that sold beer in metric units would very likely lose a lot of customers. If it is not necessary to change it is necessary not to change. A pint glass of whatever style is a very familiar object (shut up at the back). This keeps people happier except for the aforesaid tidy-minded commitee members and they are very few in number. Actually we should use cubic attoparsecs (19.34 to the pint).

I've written about this before, but beer sizes in Australia are weird and wonderful.
In Melbourne the standard drink is a pot, which is 285ml. In Sydney this same measure is called a middy, in Hobart a ten and in Darwin a handle, while in Adelaide it is called a schooner (or even an up-sized schooner as the old schooner was 255ml or 9 fl oz), however, asking for a schooner in any other city will get you 425ml. If you want 425ml in Adelaide you will need to ask for a pint, but if you ask for a pint in any other city you get 570ml. To get this size of drink in Adelaide you need to ask for an Imperial Pint. In Darwin and north Queensland (where men are men and sheep are worried) you also get a 7, which is 200ml (probably because a small measure of beer stays cold, while a big beer goes warm over time - not because they like drinking girl sizes).
It makes travelling in Australia more adventurous.

(nfras) How can a small measure stay colder for longer than a large one? It doesn't; you drink it quicker. The small Queensland measures wouldn't go down too well in Carshalton (London Borough of Sutton) where not only are men men but women are as well.

[Rosie] He didn't say it stays colder for longer. He said it "stays cold" -- presumably for the period while you're drinking it. And there's no assumption that you drink it quicker; you drink it at the same rate :-) </outpedanting>

[Phil] Is it really true that our friends on the continent can use imperial measures? I'd not heard that before, but I can believe it on the general observation that UK governments tend to believe that they must follow EU rules, whereas other European governments (notably France and Germany) know that nothing bad will happen if they don't.

I saw the moons of Jupiter last night, and very nice they were too - four of them, strung out in a line... didn't appear to be tied down at all...

[rab] It is UK legislation that has specifically outlawed imperial measures. There is no specific EU legislation to the same effect. So it is not the case that France and Germany et al have not applied EU legislation to the same extent as the UK, but that we have created extra legislation to deal with our own indecision.
This is what I have been told by someone I believe. I await correction though :-)

[Rosie] It would make no difference if beer were sold in either provided they were uniform and priced pro rata. Anyway, it would give unscrupulous barmen/maids the opportunity to short measure even more. [Phil/Rosie] my rant was about the indecision of government to go properly metric. Selling beer is pretty small beer (if you excuse the pun) it is the other nonsense that gets to me. Supermarket solids packaged in metric, liquid sold in imperial; Petrol sold in litres; building standards metric, distances measured in miles; temperature still given in Fahrenheit as well as Centigrade; metric taught at school and public weighing machines in imperial (my son was taught metric at school and does not understand pounds and ounces); the list of confusion goes on.

(Softers) Internally, railways still use chains and I don't mean the bit joining old loose-coupled goods wagons. I think we should remain Imperial because the words are part of the language and culture. Sixteen tonnes and what do you get? Deserved mockery.

[Software] Deep down, I know that standardisation is right, but I just simply love old Imperial measures (and coinage). A friend of mine who runs a flower wholesale outlet spent an entire day last week quoting all prices in old money, for fun. He didn't restrict himself to pounds, shillings and pence, oh no...tanners, florins, guineas, crowns, half-crowns and farthings were all brought into play. It made his day go by much faster.
There's a wonderful list of unusual units of measurement at one of my favourite websites, Phrontistery, which includes the dalton, the darcy, the footlambert and the face-cord. For sheer frivolity, I try to incorporate some of the words from that site into conversation, so I think it's quite easy to see why I want to cling on to Imperial measures.

(Phil) What about the threepenny bit, everyone's favourite coin in those days? There's even a building named after it.

My infant school, which was attached to the junior school I also attended (built in the 60s, I think) had a hall shaped like a 'thrupenny bit' and was known locally, for a time as 'The Thrupenny Bit School' to differentiate it from the junior school buildings, although there's no reference to it on Google, as far as I can find. It was Lacey Gardens Infant School, if anyone is interested...

[Rosie/Phil] Despite over two centuries of metrication the French still use old measures if you are worried about their eradication from the culture. They often use puce for inch, livre for pound (weight) and of course the demi for a half (pint).

[Software] Indeed, on a few occasions in France I've forgotten about that and have asked for a demi when I wanted a half-litre of beer.

(Softers) I know. Did you mean pouce? :-)

[Rosie] Oui.

[penelope] A pre WWII threepenny bit, or a post-blackout one?

(SM) Few people, even of my age, have seen the silver threepenny bit. I was once given one as change by a bus conductor about 1953 but had to spend it to get home, or walk two miles. I have found another one (1920) in my heap of old coins. They're tiddlers, 5/8" across. The chunky version was around in 1940, as I have one, and two more from the sixties. They're nice. Equivalent in the fifties to about 30p in today's money.

My mum used to have a few for sprinkling in the Christmas pud; although I can't remember ever seeing them in circulation. Here in the Channel Islands we had our own 3d bits. In Guernsey they were nickel silver with a scalloped edge and in Jersey they were round. The latter reason was why we never had 3d slots on our pay-on-answer paypghones.

I can just recall the silver threepenny bit in the Christmas pudding, but I think they'd all been lost by my adolescence. I don't know about the buying power of the dodecagonal version, but I can remember being able to buy a poke of chips for 3d around 1960.

In 1960, 3d was the standard child fare on an Edinburgh bus, 6d for adults. I remember my grandmother once showed me a silver thruppence, but I don't remember what it looked like. But here's a site with more info.