The row is over the 85-year rule, which allows public sector workers whose age and years served add up to 85 to retire with full rights at 60 instead of 65.
Unions claim that despite the disruption, they have widespread public backing.
Mr Gregson said: "There were people putting the toll money they hadn't spent in our collection buckets.
"People understand. Ten years ago, if you were talking about pensions you were probably the most unpopular and boring man in the room, but not these days."
Big day for pensions
NEW pensions regulations to encourage people to save more towards their retirement begin today.