I hate the new coins. My father must be turning in his grave

The last thing I want to do is to sound churlish. And, as the daughter of the Christopher Ironside, who designed the reverses of our current decimal coins, I knew it was going to be difficult to like the new coin-reverse designs, released last week by the Royal Mint. But I was determined to bend over backwards to find something good in them. And yet, bend as I might, I can see nothing at all in the new designs to like, and all I can hear is the creaking sound of my father turning in his grave.

It's not the young designer's fault. Matthew Dent has produced a set of designs that would do him credit in an art school project. The designs are fresh, quirky, funny, eccentric – but totally unworkable as actual coins. They're like the work of a landscape student doing a garden in the shape of a scarab beetle and expecting everyone to notice it on the ground.

Forgetting the designs – and I don't think these asymmetric angles work in a circular design at all, but that's a matter of taste – what about the absence of numerals? When I go to a foreign country I don't want to have to be an expert in the language to be able to read whether what I'm giving to a man in a bazaar is a 50 dinar piece or a 20 dinar one. I want to recognise the international language of simple numerals. We in England all know what the word "fifty" means. But it's arrogant of us to expect that the visiting Ghanaian or Japanese tourist who doesn't speak or read English to be able to read figures as words.

Then, the lettering is far too small for people with sight problems to read anyway – and because the coins are so similar in shape, it's going to be difficult to distinguish one from another.

Then there is, at the moment no £2 coin. Why not? Presumably, because it did not fit into the loopy idea that when you put the coins together you can form a picture of a shield. But coinage should be flexible. It should work so that you can remove coins – like the halfpenny and the farthing have been removed – and add coins... like the pound and the £2 coin. What happens if the penny's taken out? The whole "fun" idea will be ruined. What if the Mint decides it's time to produce a £5 coin? Where will that fit into this rigid pattern?

And rigid it is. For all its apparent modernism, the design of these coins is actually very old-hat and establishment. The Britannia and the lion symbolised the very spirit of Britain in the same way as the Marianne on the French coinage conjures up the spirit of France. This coinage is completely hidebound, sticking rigidly to the symbols on the Royal Shield of Arms. It is a strictly political coinage, not a free and open one. And not only that, but the Welsh, for some mysterious reason, have been completely excluded – and because each coin is just like a bit of a bigger jigsaw, the impression overall is of a country totally fragmented. Perhaps that was the point.

Why should my views carry any weight at all? Because I lived through the years that my father spent designing coinages for countries including Tanzania, Brunei, the Bahamas, Qatar, Dubai and Singapore. I remember him sitting squinting over the plasters, working usually through a magnifying glass in the negative, agonising whether a lion's foot should show claws, or whether Britannia's trident was at the right angle to balance with the lettering. He even designed 14 versions of the design of St George, which wasn't eventually chosen, but for each there was a reason for the small changes that he'd made.

The coins should have been designed by someone experienced who knows about coin design and understands all the restrictions, pitfalls and intricacies that it involves. Matthew Dent, a young graphic designer, who is clearly talented as a visual artist working in two dimensions, couldn't even do the plasters for the coins himself. They had to be executed by a proper craftsman, the sculptor John Bergdahl.

Surely the "primary point" of coins is not to "intrigue, to entertain and to raise a smile" as Matthew Dent declared. The primary point of coins is to be easily readable, recognisable and work as coins in the market place. And I can't believe that, out of the 4,000 designs submitted to the Royal Mint Advisory Committee, there weren't some that did just that.

It's just a pity that they chose the wrong one.