I researched the ages to the best of my ability but I ran out of time. The titled ones' ages are mostly on thepeerage.com if anyone wants to take the time.
Lady Mary Douglas-Home, 23
Lady Iona Douglas-Home, 26
(Sisters)
Their father is the Earl of Home and chairman of Coutts bank and longtime friend of the Prince of Wales. Grandpa was former PM Sir Alec D-H. Lady Iona, who is a graduate of Edinburgh University, is a state schoolteacher and Lady Mary is a "rock chick" in a band that performed at Glastonbury 2005.
Source:
London Evening Standard article, dated 31 March 2006, byline: Ticky Hedley-Dent
Some others:
Violet von Westenholz, 22,23
Victoria von Westenholz, 19,20
Laura Gerard-Leigh, 23,25?
Lady Rose Alexander, 23?
Isabella Anstruther-Gough-Calthorpe, 23? (stage actress)
Gabriella AGC, age 17,18? (a model)
Hon. Violet Magdalene Astor, 26? (from Baron Hever branch)
Hon. Flora Astor, 28? (from the Viscount's branch?)
Olivia Buchanan-Jardine, 21-23?
Emilia d'Erlanger, 23-25?
Daisy Dird, 23-25?
Lady Edwina Grosvenor, 22-24?
Natalie Hicks-Lobbecke, 26-28?
Lady Katherine Howard, 28-30?
Lady Philippa howard, age??
Lady Rosanaugh Innes-Ker, 25-27?
Alexandra Knatchbull, 22-24?
Melissa Lilley, 23-25?
Emily Mortimer, 25-27?
Catherine Palmer-Tomkinson, 23-25?
Lady Sybilla Rufus Isaacs, age?
Lady Natasha Rufus Isaacs, 22?
Zara Simmonds, 29-31?
Louisa Welby-Everard, 30-32?
Lady or Hon. (?) Eloise Anson, 24-26?
Lady or Hon. (?) Rose Anson, 29-31?
Lady Emily Compton, 25-27?
Lady Alexandra Gordon Lennox, age??
Lady Lucy Alexander, ?
Lady Marisa Agar, ? (I think she might quite a bit older, maybe 30s, but I added her because I am not sure...)