yes, 30 miles as the crow flies. If the crow takes the 'Stansted Express' as it is laughingly called it takes a while to get to Liverpool St, 45 minutes if you're lucky.
It is quite a way from Central London. There are direct rail services (Stansted Express) which take you to Liverpool St station in approx 45 minutes. It would take about an hour and half to drive to central London, depending on whereabouts in London you were going.
There is a coach from STANSTED airport to Victoria coach station or you can get off the coach at Stratford and catch the train to Liverpool St rail terminal about 8 mins] or take the Underground from there. The coach Is a flat one way fare around �8 I believe, but it could have increased.
It takes about 1hr 15mins but depends on the M11 traffic.
Coach leaves every 30 mins during the day and every hour at night.