Tax treatment of Italian Court Settlement

After 25 years, I have finally won a settlement via the Supreme Court of Cassation in Italy. I had contested the pension arrangements and payments of my old Italian employer whilst working for them as an expat. They had neglected to take into account overseas earnings in the pension contributions resulting in a lower pension. Ultimately the court agreed and i was awarded a sum over €500,000 made up of 3 parts: difference in pension arrears; interest and inflation adjustment; and compensation for the previous damage. Some Italian tax was withheld at source. Are all 3 elements liable to UK tax and if so how do i account for these on SA106? it is does not seem fair if all this counts as income due in one year making me an additional rate taxpayer when it relates to decades worth of payments that would have been taxed as a basic rate

Hi,
Further information would be required in order for this to be confirmed so you will need to provide details of the settlement in writing and send this to:
HMRC PAYE & Self Assessment
BX9 1AS
Thank you.