When it opened 20 years ago, the Selby coalfield was known for its ultra-modern "super-pits". So what's gone wrong?

Superficially, the argument over Selby is the familiar one of geology versus economics.

The National Union of Mineworkers (NUM) says the pits are full of coal, whilst the owner of the Selby pits, UK Coal, says digging out the fuel is uneconomical.

But Selby's super-pits have also fallen victim to some wider trends which have beset the UK's coal industry.

What trends?

The glory day of British mining were clearly over at the end of National Union of Mineworkers' (NUM) year-long strike in March 1985.

Not only did the NUM's power-struggle with then prime minister Margaret Thatcher show that miners lacked the massed industrial muscle of the past.

Ironically, it also revealed coal mining was no longer vital to the UK economy.

Since then, Britain's biggest mining firm has struggled to reinvent itself to cope with more competitive global coal markets.

Miners in Yorkshire's Selby coalfield even set records - which remain unbroken - for annual and weekly productivity in 1993.

But the firm has struggled to combat cheaper coal imports, and cleaner fuel concerns which led to the so-called "dash for gas".

Gas-fired power stations produce lower levels of greenhouse gases than coal-fired ones, helping countries meet commitments for lowering emissions of greenhouse gases.

Demand for natural gas is growing at twice the rate of demand for coal, and 50% faster than demand for oil.

What impact will the closures have on Yorkshire's economy?

There's no doubt the impact with be harsh.

UK Coal says it injects �400m into Yorkshire's economy a year.

As well as the 2,100 miners in the three Selby pits, many thousands more workers depend on the industry.

For instance, UK Coal estimates mining machinery manufacturers contribute �34m a year to the regional economy.

But the impact of redundancies, however harsh for individual miners, whose average age is 45, is likely to be less devastating for small communities than in the past.

As the industry has shrunk, many miners are driving up to 40 kilometers to work.

So will the government help out?

Gordon Brown is expected this week to announce about �40m of aid to help the Selby coalfield cope.

The package is expected to include �10m towards the compensation package, which will pay out a maximum of �27,000 per mineworker.

But the government has refused to bend to calls for more widespread subsidies.

UK Coal's chief executive Gordon McPhie, for instance, has complained of discrimination, saying German and Spanish rivals get more aid.

But Trade Secretary Patricia Hewitt told local MP John Grogan in May it was "not possible" for the government to back investment in the coal industry because of EU rules.

The future of coal mining - and, more importantly, coal miners - has been a politically sensitive issue for the Labour government, which has trod carefully.

The first Blair government agreed to a two-year ban on the building of new gas-fired power stations. It won �110m in aid from the EU for the coal industry.

But in 2000, the then trade minister, Stephen Byers, gave the go-ahead for the construction of six gas-fired power stations.