Which airlines provide laptop power supplies?

[papalazarou 0]

Can anyone tell me which airlines flying from London to Thailand provide this feature, especially any that provide it in economy.

 

TIA

[Severn 109]

I flew with Quantas last november and they appear to have power for laptops in economy.  BUT..... It appears that you have to buy a converter from them at a cost of about 34 pounds.