The last of the original 47/4 conversions, from 47650 to 47665, were fitted with extra fuel tanks, giving them an extended range. Four earlier Class 47/4s were also converted.

In 1989 it was decided to give these locomotives easy recognisability, and so these locomotives were renumbered into their own series from 47801 to 47820. At the same time, further locomotives were fitted with extra fuel tanks and renumbered; the series eventually reached 47854. After the privatisation of British Rail, the locomotives in the 47/8 number range were mainly used by Virgin Trains on cross-country work until the introduction of their Voyager trains. As their duties required them to be in service until late in their careers, this has meant that they have remained operational longer than the majority of their classmates. As a consequence most of them received relatively recent overhauls.