(Future price of) Natural Gas is more than 32 times what it was eighteen months ago.
https://en.wikipedia.org/wiki/Dash_for_Gas
“An underpinning factor in the dash for gas was the recent development of North Sea gas.
In 1990, gas turbine power stations made up 5% of the UK’s generating capacity. By 2002, the new CCGT power stations made up 28% UK generating capacity; gas turbines accounted for a further 2%. It is estimated the Dash for Gas cost £11bn.”
The conservative government was in power from 11 February 1975 till 2 May 1997.