Priority pass have the following on their email update on new lounges:

"We would like to welcome the Club Millesime to our lounge program. This luxurious landside lounge is accessible to all Priority Pass Members, both traveling to and from London Heathrow Terminal 5. During your stay at the Club Millesime you can enjoy an array of fine wines and canapés, as well as complimentary showers access, all in an exclusive relaxed setting, ideal for both the business traveler and leisure guest."