Welshman Gareth Delve ensured an English victory in the dead rubber match at Rodney Parade.
Early penalties from Willie Walker and Ceri Sweeney were added to by a try from front rower Adam Black in the first half.
Sweeney added a second penalty after the break to push the Dragons further ahead but a try for Delve at the death, complete with conversion from Scotland’s Chris Paterson sealed the last-gasp win for Gloucester.
