Rob, I believe otherwise, never seen a picture of steam, comming out the whistles.
The only reference I can find to back me up so far is 'From the Bridge - QE2 Cunards Flagship' by Peter Moxom, Malcolm Finister & Allen Burnley which just happened to be to hand, on page 57 there is a photo of the mast and the description underneath describes the items on the mast, it reads: ''The Mainmast, showing from bottom to top: the DF areial loops, the 3cm radar scanner, the 10cm radar scanner and the electric and air-controlled whistle horns.''
Page 32 of the same book refers to one of the whistles as a 'Tyfon Air Whistle' and refers to the Master asking permission of the Harbour Pilot to sound it three blasts upon departure from Southampton.
Haven't time now, but later will research further, many other books to go! Look forward to hearing what others find!