This was introducted about a month ago:
Seat Alerts - Be alerted when the seat you want becomes available - ExpertFlyer Blog
Works well. BA has a habit of moving the curtain between J and Y forward as a flight gets closer (and also backwards too sometimes if J sells well). I was able to know very soon after they released my favourite seat that it was available, so snaffled it.
	
		
			
		
		
	
				
			Seat Alerts - Be alerted when the seat you want becomes available - ExpertFlyer Blog
Seat Alerts allows you to be notified if a currently occupied seat on your flight that you wish you were sitting in becomes available.
Works well. BA has a habit of moving the curtain between J and Y forward as a flight gets closer (and also backwards too sometimes if J sells well). I was able to know very soon after they released my favourite seat that it was available, so snaffled it.
 
				 
						 
  
 
		 
  
 
		