I know it's a long shot, but giving MN a try on this...
My sister, who lives in Croydon, has been let down at the last minute by an au pair who was due to arrive this week. She needs someone ASAP. I just wondered whether anyone in that area might know an au pair looking for a new family, or perhaps someone's got a great au pair whose sister/cousin/friend wants to come over here and live nearby?
TIA