Hi aznkix,
sorry to tell you - but your dad is screwed as he will definitely need a visa.
As your mum is British, while also living in Britain, the EU-law that governs visa-free-travel does not apply. As a result he will definitely need a Schengen-Visa.
However, as your dad is married to an EU-citizen, this visa has to be dealt with "at an accelerated speed" without "undue formality".
Edit 11h59: Sorry - just did some research. It does NOT HAVE TO BE dealt with according to the above, but you can hope for it anyway, as they all have no clue as you will find out...
This means that your parents (only) have to produce:
- both their passports AND
- their marriage certificate
You will read different information on different Schengen-countrie's websites, but what I am writing here is the correct law, of which not all of the embassies are aware.
In specific, some of them will ask you for flight-tickets, hotel-reservations and some other stuff, all of this is, in your case, ILLEGAL.
For practical matters I recommend you to ring all Schengen-countrie's embassies in London (or if there are any, closer to where you live), and ask them how they want to proceed in your case.
As soon as you get through to an embassy who deals with this as I described above, stick to them! Tell them you want to visit their respective capital, and you want the visa.
You will not have trouble entering Italy with any Schengen-Visa.
Schengen-countries are:
- All countries of the EU, except the UK, Ireland, Cyprus, Bulgaria, Romania
- aditionally (outside the EU) Norway and Iceland.
It will be a task for the afternoon to find their contact-details and ringing all of them.
If you decide to follow this advise, please let us know how it goes...