I have been offered a contract position for 6 months based out of London. I have also cleared telephone round for a permanent position based out of Edinburgh, the f2f is being scheduled.
The contract role pays about 25% more than the permanent position, but this will be levelled, considering the cost of living in London.
My Tier 1 runs out in 12 months, it makes more sense to take up the permanent (provided I clear personal round) as my extension will become secure. The risk with contract is that, if it doesn't get extended in 6 months, then there might be a gap of couple of months before I secure my next role, which can pose a problem for extension.
Other points,
1. My wife is also pursuing her job search and it makes sense to be around London as options are more.
2. The contract role is with a well known international brand name and the work is good, while the permanent role company is a good company to work for, am yet to find out more in detail about the work.
Are there other points I should consider before making the decision to go for the contract role or the permanent position ?
I know all of this is only valid if I clear my personal round with permanent role company.

Would really appreciate your valuable suggestions and opinions.
Thanks,
OR.