But now, the 79-year-old says he is being forced to quit the beach, blaming a track and fence being built by the Dunedin City Council for blocking his access.
Mr Robertson told the Otago Daily Times the fence would run between his coastal Brighton Rd home and the beach, blocking his own informal track leading from his home through sand dunes to the beach.
Mr Robertson used his track to take horses on to the beach, and learned of the council's plans only when a letter arrived in his mailbox last month, which was followed by heavy machinery on the site.
He said the council's move had ended his use of the beach after a lifetime spent developing "dozens" of winning horses there.
"It's going to be awkward now to work the horses... I have held a trainer's licence longer than anyone else in New Zealand. I was first to work on the beach and I'm going to be the first to be put off," he said.
Council parks officer Renee Gordon confirmed the new fence would be installed beside the newly-completed access track.
The new track, stretching about 1000m, was an extension of a walkway on the southern side of nearby Taylor's Creek, and aimed to stop people trampling over the dunes while taking direct routes to the beach.
The new track ran parallel to the beach, towards the back of the dunes, and connected with several other already established council pathways to the beach, she said.
The new track was not for horses, but she believed Mr Robertson could use a horse float or take his horse to the nearby access pathway at the Ocean View car park, which was wide enough for horses.
Mr Robertson said the new access track was too narrow for his horse and jogging cart, and there was not enough room on his float for all his equipment.
Shuttling to and from the beach would add an hour each way to his training schedule.
There also was not enough room on the side of Brighton Rd to avoid traffic while driving his horse in the cart 300m to the Ocean View car park, and he was reluctant to brave the open road, he said.
"You would get killed. They [motorists] have got no sense of what a horse is like. Some of them deliberately toot a horn to frighten a horse."
Ms Gordon said she had not heard from Mr Robertson, but concerns raised by other residents had led to compromises.
Plans to fence both sides of the track had been scaled back, with a fence to be built only on the track's seaward side, to protect the dunes closer to the beach.
A fence on the track's inland side had been scrapped, allowing residents' informal tracks to link to the council track.
About 27 properties along Brighton Rd were directly affected by the fence and letters advising of the work had been sent to 100 homes.
Beach access would be maintained at several points along the track, including the Ocean View car park.
Council bylaws prohibited horses from the beach, but staff had turned a blind eye in the past because the established beach access tracks were good, Ms Gordon said.
The track and fence work was expected to cost about $10,000 and was being carried out as part of the council's dune conversation works programme, approved in 2002 following public consultation, she said.
About 2000 plantings were also to be added next year, as part of revegetation work in the area.
