The tax was a political stunt from the start. Gideon Osbourne knew that the oil companies would just charge more for fuel but the proportion taken in direct taxation on fuel was reduced. he would look good and oil companies would be reviled for increasing the price to cover the tax.
As for the gas field, surely no-one expects a politician to see beyond the end of their own ideas.
Geography is not the Telegraphs strong point?
I also think the area was closed for maintenance. I can't see them keeping it closed for too long unless they get ride of all the crews who work the area to save money. It would then be expensive to reopen when the price goes up. All those crews will have to be retrained and re-qualify to work off shore.