Three have launched a new app called Wuntu and one of the deals on there is a £13 a month sim only deal for 12 months. Looks like it's a nano sim but can be used in any phone with an adapter.
The contract has 30GB of data, 200 mins and unlimited texts. (And tethering) It also includes three's feel at home which you can use your data in 42 destinations at no extra cost.
After 12 months it turns into a rolling contract.
Looks to be a really good deal (this may be for existing customers only with the wuntu app)