A number of biz jets use SEN including Ford's shuttle oper to CGN. There is plenty of space and the airfield is 24 hour with good wx conditions all year. Journey from central London is dependent on traffic volumes and on a good run, between the hours of 0700 -1900 you would be lucky to do the journey in under 90 minutes. During these hours the Southend arterial road can also be a problem. that said the airport has had bits of the terminal refurbished and is making slow progressive improvements, that may include a railway station next year. It is at present up for sale with a 130 year lease left but it also is reputed to require 30 millions to be spent and increase runway length.