The case of Burma Oil Co V Lord Advocate shows that the UK government has the power to create retrospective laws
During World War 2, the UK forces bombed, deliberately, Burma Oil Companies supplies. This was to prevent the Japanese from gaining access to them. After the war the company, Burma Oil, sued the UK government for the loses.
To avoid paying the costs of the UK created a law called the War Damage Act, 1965, which was to be put into effect retrospectively.
This case, Burma Oil Co V Lord Advocate, upheld this, this meant that that Parliament can create laws that can be enacted retrospectively.