I haven't got any data to back this up, but my suspicion would be that most European families would expect to book a second room, perhaps with connecting door, if there was a teenage or adult child(ren) in the travel group. But for the Hilton London Angel Kings Cross - not the Doubletree with the similar name - they do have some reasonably large rooms with two double beds, under the "Deluxe Room with two Double Beds" title and they would probably meet your needs. Very similar to the West Wing at the Metropole, however unlike the Metropole there are only a few of these rooms (6 or so) in the Hilton Islington, which isn't a big hotel, 188 rooms in all.