User summary, based on information from English Wikipedia's Virgin Interactive entry, Mastertronic entry and Avalon Interactive entry:
Virgin Mastertronic was born in 1987 as the distributor Virgin Games (founded 1981) bought the budget games publisher Mastertronic after the latter suffered cash flow problems after the acquisition of Melbourne House and because the budget market was declining. Virgin did so to get ahold of the Sega Master System distribution rights, that Mastertronic had managed to seize.
In 1994, the company changed its name to Virgin interactive, which subsequently was bought in 1999 by the French publisher Titus software and renamed to Avalon Interactive in 2003. Both these companies have ceased trading.