It’s organised by the Silston AC (also known as Silston Joggers). Their website’s page for the 10 km is here: http://www.silsonac.org.uk/silverstone-10k-grand-prix-race/

As a general rule, they only put details up of a given year’s race when they’ve confirmed the date and sorted out other basics – they’re not like some organisers, who put up the date for next year’s race at a given year’s running or soon afterwards on the assumption things will remain static from year to year. This is why, at present, they just have the information from last year posted.