I HAVE an incurable fondness for old jokes, and one that sprang to mind last week was of about Second World War vintage, relating to the packs of cheap cigarettes dished out to overseas troops.

A soldier who smoked these found himself in the factory where they were made and he watched as a worker put two shovelfuls of tobacco into a hopper for every three shovelfuls of camel dung.

When a factory manager hastily tried to move him on, the soldier said: “No, no, that’s good – I thought they were entirely camel dung.”

That old chestnut sprang to mind when a make of frozen beef lasagne was last week found to be 100 per cent horse meat. Never having bought a Findus frozen meal, I’ve no idea what that “beef” lasagne cost, but I assume it was cheap.

And as has been said time and again since traces of horse meat were found in cheap burgers, the message is that if supermarkets force a chain of suppliers to provide what they want at cut-throat prices, then shoppers who think they are getting a bargain are in fact being cheated.

Yes, they’re paying low prices – but getting rubbish.

Not only because they don’t know what the meat is, in spite of what it says on the label, but because – again in the case of the Findus lasagne – the main ingredient was water. How about that for inspired marketing?

I know all the arguments about who can afford what. The fact remains that economising on food does not mean buying the cheapest available pack. It means, for example, buying a chicken to provide one family meal, carefully removing all remaining meat and adding mushrooms and piles of pasta to make a second meal, then boiling the bones to make stock as a base for soup.

The cost of a chicken carcase and vegetables to make a big pan of soup compared with a frozen lasagne? You don’t need to be a maths wizard, do you? But you do need to take what you eat more seriously.

No one is going to change the public’s approach to “cheap” processed foods, fizzy drinks and crisps over a short period, as a glance at any supermarket check-out line of trolleys will confirm.

But a food chain that sees horse meat from Romania eventually appear on British supermarket shelves as beef must make more think again about what they’re buying?

It must also, surely to goodness, put more pressure on the big supermarkets to treat suppliers more fairly? I hope that the formidable Christine Tacon, recently appointed as groceries trade adjudicator, has a part to play in that.

Ms Tacon was chief executive for the Co-op’s farming business, turning a £6million annual loss into a £6million annual profit during her time there. She’s going to be paid £69,000 a year for three days a week to act as – journalistic shorthand – a watchdog on supermarket practices regarding suppliers.

Compared with many farmers trying to make a living, that’s big money. But if she can do the job I think she’s capable of doing, of forcing supermarkets to treat suppliers as free men rather than serfs, it should be money well spent.

The problems of 2012 for farmers trying to make a living were confirmed last week with publication of total income from farming figures for Scotland. That’s looking at Scottish farming as one business and finding that total income – the difference between income and costs – was down from £746million in 2011 to £635million in 2012.

We should bear in mind that 2011 was a good year. But last year – much of the distress caused by the appalling weather – there were lower yields, increased costs and an unfavourable currency exchange rate.

Most farmers need look no further than their own bank statements and accounts to know that. But itemised on a national scale the effect is emphasised.

Estimated value of production (outputs) fell by only one per cent, lower grain yields to some extent offset by higher prices. But costs (inputs) rose by £219 million, 13 per cent, in 2011, and by a further £44million last year.

For farmers in England the forecast is that lowland beef and sheep producers will suffer an average income drop of 44 per cent, to £18,000, while upland beef and sheep farms will see a 52 per cent average slump to about £14,000.

A more personal view of last year was given at Merse Agricultural Discussion Society last week by Geert Knottenbelt, manager for Alan Stevenson’s Luffness Mains, Aberfeldy, arable farming operations.

The main part of those operations is potato growing and last year yields on the several hundred acres grown slumped 17 per cent, quality fell and harvesting in wet fields was a nightmare. So much soil damage was caused that several farmers in East Lothian from whom the Luffness operation has rented fields for years have refused to rent them land this year.

Are the supermarkets worried by growers’ problems and that a fall in Scotland’s potato acreage could mean shortage? No, because they already have agreements in place for imported supplies. Marvellous, isn’t it?