I have some old postcards from my grandmother with three halfpence stamps on them. (scroll down a bit)
Leaving aside the historical currencies mentioned above, the answer to the OP is very simple:
There’s 100 pence (100 pennies) to a pound. Quid is merely slang for a pound. You already know the exchange rate, although you’re estimating quite low - £1 is currently $1.63.
It’s worth remembering, though, that the actual purchasing power of the pound in the UK is not as high as that exchange rate suggests. A lot of things cost almost as many pounds in London as they cost dollars in New York, say.
Technically speaking, the pound is £, while the lira was ₤. Sometimes they are used interchangeably, like how $ can have one or two slashes, or if it’s easier to type one on your keyboard.
It did just fine as long as we were using half new pennies - 2/6 old style was 12.5p new, so it was still an exact conversion. It wasn’t until the Eighties that we stopped using the 0.5p coin.
Well, they would be, yes. In which case, the confusing aspect of your post is the suggestion that they ceased to be legal tender in the 1970s.
Did the Brits actually declare valueless some of the more offbeat coins, or just stop making new ones and gradually withdraw them from circulation as they drifted into banks?
And to think that not only was it once that cheap to mail letters, but the mail carriers delivered and received your mail several times a day!
I don’t think many Americans outside the coin collecting world are aware of it, but through most of the nineteenth century our mints experimented with a variety of oddball denominations, including 2c, 3c, half-dimes (worth 5c like a nickel, but silver and very tiny), and 20c (for those desiring a slimmed down version of the quarter I suppose). In gold besides $1, $2.5, $5, $10, and $20 coins that circulated widely there were small issues of $3 and $4. The first four gold denominations are still within the cultural memory for us who are old enough to have parents or grandparents who remember using such coins. For instance, my grandmother used to tell me that as a young office worker in the 1910s she might receive an eagle or half-eagle as a holiday bonus.
OK, as I understand it… this is what happened to the everyday coins in circulation before decimalisation:
Farthing (1/4 old penny, 1/960th of a pound) - demonetised in 1960 for being too worthless.
Halfpenny (1/2 old penny, 1/480th of a pound) - demonetised in 1969, shortly before decimalisation.
Penny (1/240th of a pound) - demonetised shortly after decimalisation in 1971.
Threepenny bit (3 old pence, 1/80th of a pound) - demonetised shortly after decimalisation in 1971.
Sixpence (6 old pence, 1/40th of a pound) - remained legal tender as 2.5 new pence until 1980.
Shilling (12 old pence, 1/20th of a pound) - circulated widely alongside the new 5 pence, which had identical value and size of coin. Demonetised in 1990, when a smaller 5p was introduced.
Florin (2 shillings, 1/10th of a pound) - circulated widely alongside the new 10 pence, which had identical value and size of coin. Demonetised in 1993 after smaller 10p introduced the previous year.
Half-crown (2 shillings and sixpence, 1/8th of a pound) - demonetised in 1970, shortly before decimalisation.
Crowns (5 shillings, 1/4 of a pound) were IIRC not in common circulation, being used as commemorative issues.
Ten bob notes (10 shillings, 1/2 of a pound) were demonetised in 1970, having been replaced by the decimal 50p coin.
(Note that the decimal coins that had exact equivalents in the predecimal currency actually began circulating BEFORE decimalisation - IIRC, the 5p and 10p coins began circulating alongside shillings and florins in 1968, and the 50p circulated alongside 10/- notes from 1969.)
Nowadays, the only widely circulating coins are:
1p
2p
5p
10p
20p (introduced in 1982 to fill the gap between 10p and 50p)
50p
£1 (introduced in 1983 to replace the £1 note)
£2 (everyday issue introduced in 1997 - before that there were occasional special issues)
As mentioned above, commemorative £5 coins are issued each year (or most years), but are hardly ever seen in circulation.
Banknotes are £5, £10, £20 and the rarely seen (and not very popular with shops) £50.
1990? That long ago? Man, I’m glad I hung onto a shilling or two I picked up on my first visit to the U.K.–in 1989!
I hate change in my pocket and it would take them to stop printing 1 dollar bills for me to switch. I have just been using money to long to change my customs
I was wondering about this and nearly opened a thread about it. So it’s also common there not to accept any notes higher than twenty pounds, the way many businesses here will not accept higher denominations than $20? It generally tends to be small retail outlets who are more exposed to possible robberies that do this, and one can see the logic in it. Still, that leaves only two or three commonly circulating notes diminishing the variety that we see. If we ever get rid of the $1 bill, that will leave essentially only fives and twenties in active circulation, since tens seem to be slowly disappearing from circulation.
Then why do the US refuse to use 2c and 50c coins, or $2 notes? Every time I go there I end up with a pocket full of pennies. And they refuse to ditch pennies altogether, come to think of it.
Well, we do have $2 bills and 50¢ pieces (Kennedy half dollar, still popular in Vegas for paying off blackjack bets). American cash registers don’t have enough slots for $2 bills or half dollar coins, which decreases their popularity. Apparently we had a 2¢ coin between 1864 and 1873.
The two dollar bill is pretty cool, with Thomas Jefferson on the front and the signing of the Declaration of Independence on the back. I’ve got a bunch of them and give them away to foreign visitors as a souvenir.
It would make a ton of sense to get rid of the one dollar bill and the penny, but Americans are extremely conservative when it comes to their monetary designs. There was a pretty big hullabaloo when we first switched to the big head Ben Franklin C-note.
I once took 450 million lira from an ATM in Turkey - hard to get all the zeros right.
I went to dinner with a friend in Jordan who was new to the Arab world. The Arabic 5 looks a bit like a zero except it is a bit of a rounded triangle. The Jordanians have a 5 fils coin that just has an Arabic 5 on the back. So it was great fun when she said “What kind of country produces a coin worth zero?!” 
The US will never have a dollar coin that works until they get rid of the paper note. And why they can’t make a two-tone coin like so many other countries is a big mystery.
And why do Americans refer to a cent as a penny?
We don’t refer to our pennies as cents.
+++++++
In the Channel Islands as well as having all the UK coins listed by Colophon they also have £1 notes
Back in 1971 I was working in Harrods, and on decimalisation day, and for a while after, I was given the job of wandering around the store explaining to the little old upper class ladies that, no, Harrods aren’t ripping you off just because a shilling used to be twelve old pence and now is five new pence. They just didn’t get it, and became really quite irate.
Addendum: You could use old pennies, threepenny bits and so on, up to a round multiple of 6d (2½p) not less than the asking price, and receive the change in new pence. The shopkeeper banked the old currency, so the old small change disappeared from circulation through natural wastage. This was a theme reiterated in “Decimal Five”, a series of BBC infomercials by The Scaffold - in this case the catchy jingle was “Give more, get change (do what you’ve always done)”. So if you had to cough up 17p, you could pay 3s 6d and receive ½p change; if it cost 18p, you could pay 4/- and get 2p change, and so on. It worked quite painlessly.
Although chaos and confusion was widely predicted in Feb. 1971, the actual changeover process proved to go quite smoothly, and, looking back in a TV programme in 2001, the theme was ‘what was all the fuss about?’ (with the unspoken subtext of, ‘when we’ve joined the euro, you’ll look back in thirty years and say the same’)
Nah, I’d tend to side with the Official Monster Raving Loony Party and invite the rest of Europe to join the pound. Also in favour of their policy regarding MP expenses. 