Forging £1 coins is apparently profitable

Three men have been convicted of forging £1 coins. The London Police Detective Inspector even got all quippy about the sentencing ("These three men are organised criminals who were intent on undermining the UK monetary system. There is nothing fake about the reality they must now face of life behind bars." -- yes, yes, very clever DI South) but what fascinates me about the story is that it can somehow be profitable to forge £1 coins.
I got passed a fake pound shortly after I first moved to the UK, almost ten years go; it was a foil-wrapped plastic slug. Not realizing it was fake, I tried to buy something with it at a corner shop and the cashier pressed it edge-on on his counter and the foil split open, revealing the green plastic disc inside.
From the sound of this article, these fakes were solid metal, which, I think, would make them more expensive than the fake I got. When you add the costs of the materials, the wages for the manufacturing process, warehousing, the discount for counterfeit cash, etc, it's hard to believe that this was worth anyone's while.
On the other hand, it's probably easier to go on counterfeiting when you're passing very small denominations as most people (me included) won't bother going to the cops over a mere pound; and it's much harder to remember where a given pound coin came from than a £20 note.

The court heard Fisher, of Rags Lane in Goffs Oak, Hertfordshire, Sullivan, of Bancroft Chase in Hornchurch, east London, and Abbott were arrested during an undercover police operation in Essex last May.
Police found a storage container with 1.6 million metal discs inside and fake coins equivalent to £20,000.
Fake coins equivalent to a further £30,000 were found in a nearby car.

Three men jailed over 'largest' fake £1 coin plot