This is a Celesta made by Mustel of Paris.
Victor Mustel invented the Dulcitone in 1860, but it was his son Auguste who invented the Celesta (or Celeste) in 1889. However this particular model was built by Victor and is clearly signed by him.
This one is ex-BBC from the Maida Vale studios and has been used and featured on many recordings and broadcasts over the years. It sold for £2,650 on Ebay. I think this is a good price - new ones are very expensive indeed.