I think regardless of the tax benefits discussed in this thread, even with an equal playing field you will earn significantly more than your permie peers.
You can get 50k if you're lucky in London, but you can earn 500 a day as a contractor.
500 * 230 conservative work days per year = 115,000 NET
230 work days aren't "conservative", that's 4.5 days/week. Given the legal minimum of 28 days holiday per year for permanent employees (28 includes bank holidays, often you'll find vacation quoted as 20 days which doesn't include the bank holidays), that's close to 100% "found work" rate.
Ten weeks holiday and still earning over 100k contracting a year at £500 a day. Obviously not everyone has a contract all the time but from my friends that do contract they almost always are working (and they are outside the market hungry center that is London)
Speaking about holidays, what's the employers' attitude towards days off say on a 3 or 6 months contract? Can you take a week or two off during a 3 month contract or you are generally expected to work the full contract time?
Clients can't prevent you from taking time off, you have a complete freedom to choose how much you work in theory. Having said that taking a week or more off during a 3 month contract will no be expected by most of the clients. Taking a day or two off is usually not a problem. It really depends on the client.
You can get 50k if you're lucky in London, but you can earn 500 a day as a contractor.
500 * 230 conservative work days per year = 115,000 NET