Virgin Atlantic has been flying from London Heathrow to Schipol Airport, the Netherlands, in a series of trial flights, according to 24 oranges, a Dutch blog in English. Gina Cobb is neither insightful or offering a very useful perspective on her blog about the proposal to use 20% biofuel blend. But then I guess she's playing it for laughs.
Howver, Flight Global has the Virgin Atlantic test flights happening next month. I'd rather believe that source.