Thanks for the replies. Finally got through to the rtb and their advice was, while not obliged to list the addresses, it was best to do so as the tenant could request the info on receipt of the notice. Also asked them about definition of "comparable" as was finding it difficult to find similar properties both size and location. Their advice in this was location over size but then followed that with "even if that means a property 30 miles away. Bizarre! I gave up at that point and thanked him for his time.