They have always been 'private land', even as a nationalised company when British Rail.
Of course NR only control the largest and most prestigious stations on the network, although I can see that other train operating companies like Virgin will no doubt have a go with their stations if there is money in it. (and Virgin/Stagecoach have fingers in pies for the East Coast, West Coast and East MidlandTrains, South West Trains, etc etc). Quite surprised at the outburst from Alamy though; have none of their photographers ever been stopped and questioned before? Saw a well known journalist pulled up at Birmingham New Street a few years ago and thrown off the station for it, because he argued. He wrote a few miles of column inches but he was wrong and it made no difference anyway.