I went to a speed dating event recently in central London and left after an hour. Really disappointed with it. Half the women didn't even live in London (one was actually on holiday from America), most were overweight, and very few were professionals (one woman talked non stop about nandos). The rounds to chat to people are only 3 minutes which is far too short.
The bar itself is dire (its changed its name to Forge but used to be Apt). It was an utter waste of time.