Legal marriage /registry office in

No and yes. You need a collection of documents from the UK - including the nulla osta which must be translated and submitted to the Italian authorities in advance - you need to start planning your documents at least 4 months before the wedding. Once you have them, the actual process is pretty straightforwad - and you will need a transaltor here if the spouses dont speak Italian well.  There are loads of wedding websites which list what you need - make sure the info is uptodate - it all changed just over a year ago. 

HelloI got married in a comune in Liguria. The first thing I did was book a date with them and I was surprised that the booking & ceremony was free.  I had to do the banns in the UK and then get the certificate of no impediment translated into Italian and the document legalised. This document also had to be legalised by a court in Italy which was not costly. My Italian friend acted as a witness and translator at the ceremony. I did the whole process in about 3 months. I hope this helps 

Sorry robbiemarche I totally misread your post. Our daughter married in Italy 2007, so a while now and had never even been on holiday there let alone resident. So no, you don't need to be Italian resident, although I'm sure they did have to spend a few days there prior for some reason.

GETTING MARRIED IN ITALY: PROCESSThanks Steve - very reasured now.Process seems to be:

1. Book appointment and attend at your local UK Registry Office with passport (or birth certificates) and bank statements
2. (In meantime, book date and time for ceremony at local comune in Italy)
3. 29 days after appointment the 'Certificate of No Impediment' is issued:  cost £40-£60
4. Statutory Declaration sworn before any solicitor - 1 day
5. The certificate legalised at the UK Governement Legalisation Office: 5 days  (Cost £35.50 inc. courier fees)
6. Legalisation in Italy - if you are there: 3 days
7. Lodge papers with Town Hall - 3 days before ceremony
8. Note: Some comunes require local banns to be read - 8 days
9. Ceremony at local Town Hall (20 mins):  Typical cost 100-350 euros deoending on comune and location/office of ceremony

I can confirm like the others have already mentioned there were no issues being a UK resident. The hardest thing is getting the documents translated and legalised including birth certificates. Good luck !