Only just found this topic as I was searching for something else related to this 'line of sight' subject.....went up Blackpool Tower back in November 2016 and for the first time in all my trips up to the top, I was able to see Liverpool clearly, for reference, the Radio City Tower which can be made out as a thin stick about 1/4 in from the left on the attached pic, is 28.48 miles according to Google.....have managed a shot the other way from Liverpool (top of the Radio City Tower, formerly St Johns Beacon) looking towards Blackpool (where the tower could be made out....) but can't find it at the mo....also visible are the cranes at Seaforth Docks and various other tall buildings in the city.....