Two I can recommend, ditchling devil and London Oxford London.I don't think there's many Sportive's for that distance. However, head over to the Audax UK website. You will find a lot of rides at that distance and above.
The Ditchling Devil Audax is an excellent day out. 200k, plus riding to/from the start should give you 150mi.
The Great Escape is good too. Much flatter than the DD.
Have a look at www.aukweb.net
Both have the problem of urban London riding and fiddly navigation in the final stages. A bit worse for TGE.