I used the Skyteam lounge at Heathrow by paying £25 yesterday. Although expensive, I had >3hrs for my flight to Mumbai. Food was decent and ambience was good with reliable wifi connection as well which allowed me to finish up some work.
Bonus is that it tracked as KLM Royal Dutch Airline in my credit card payment (email and sms)and so good to get some bonus miles given the recent offer from Citibank Premier Miles card for overseas spends.