@flash2005 it is well established that the Italian authorities have zero ability to enforce these outside of the EU, and to be honest even before we left the chances of them enforcing via the UK courts was close to zero because under the EU cross-border scheme for the enforcement of fines, the enforcing court gets to keep the money.
So, unless you plan on moving to Italy, you can throw the penalty in the bin. You might get a couple of letters from toothless debt collectors who who you might cough up, but that would be the end of the matter. The only reason they issue any correspondence at all is because they know that for every 100 letters they send, they only need 1 person to pay to cover their costs. If 20% actually cough up, they make an absolute fortune (at least compared to the 0% collection rate they'd get if they didn't even try).