I have a full UK drivers licence and have completed my CBT (compulsory
Basic Training) safety course. I am legally allowed to ride my 125cc
Vespa scooter in the UK with L plates affixed, but am not allowed to
carry a passenger. Am I allowed to rent a 125cc scooter in ITALY, and
carry a passenger? So, can I rent a 125cc scooter in Italy (likely
Rome) with a valid UK car drivers licence (not a motorcycle
licence)and carry a passenger?

Howdy andrewgparker-ga,

This Frequently Asked Questions (FAQ) page on the Rome-based "Cyclo" website
covers your question, and leads to the answer.
http://www.scooterhire.it/faq.asp

"1) Are the 50 cc. vehicles approved to transport the passenger?
...
To be allowed to transport a passenger the Customer should rent a class G or
a superior class. Classes A, B, C are not allowed to transport passengers."

This page on the same website clarifies what a Class G or above includes,
and if your UK drivers license for a car is enough.
http://www.scooterhire.it/cat.asp?Cat=2

"...
- On all scooters of this page can ride two people.
- No special motorcycle license required for classes F G H but just a driver
licence for car.
...
Class G-100/125 cc
..."

If you need any clarification, please feel free to ask.


Search strategy:

Google search on: rent OR rental scooter Rome OR Italy passenger
://www.google.com/search?q=rent+OR+rental+scooter+Rome+OR+Italy+passenger

Looking Forward, denco-ga - Google Answers Researcher