London is still not showing for Helvetic via thier on line booking system.
Farnborough is limited to 28,000 movements per year and only 2,500 of these can take place at the weekend or bank holidays. Hours of opening are:
Weekdays 0700-2200
Weekends 0800-2000
Therefore the airport is shut for around 69 hours per week, that is almost 3 days!
An added priviso to the yearly movement rate is that there must be no more than 20,000 movements of the average type of noise distubance generated during 1997. Basically encouraging quiter aircraft to use Farnborough.