The WHIR holds networking events at US cities throughout the year which appear to be very popular. This autumn they’ll be holding two such events in Europe.
One in Amsterdam and one in London. (This isn’t the first time that they’ve done events in Europe.)
The event in London is being held on Tuesday September 29th. As far as I know that doesn’t coincide with any specific event(s) in London.
If you’re interested in attending either event you can signup online here.