That Frank was set to leave was something of an open secret at Upton Park even before the departure of his father and uncle left the club, and one of the first tasks Harry's successor will have is to identify a suitable replacement for him.
That, says Harry, won't be easy, and he rejects claims that Frank ever benefited from nepotism at the club.
"Frank is one of the jewels in the crown," says H, "and he had to be more than good to get into the side.
"If anything we held him back, and when I used to hear people say 'he's only in the team because of his uncle and dad' early doors, it was the greatest load of nonsense.
"It showed you that the people who said that knew nothing about football because he went on to play for England, and it certainly wasn't me picking the England team, and nor was it his dad.
"It just shows you what idiots they were; these were bitter and twisted people, and that's something I'll never be.
"These people had a real problem with themselves, but he has proven to everybody what a great player he is."
A meeting with Frank junior last week confirmed to the Hammers' hierarchy what had been on the agenda for some time: that Frank felt he needed a change of scenery.
Although no bids have yet been received there is certainly a lot of interest in the player both from within these shores and abroad.
Harry adds: "Frank is his own man and always has been; whatever he does next he will be a top player."
Harry admits he was disappointed that Frank senior left at the same time as he did, saying: "He was West Ham through and through."
Harry hopes that the new man has plenty of success in the transfer market, and says: "The board are sitting on an absolute fortune, a goldmine; if someone wants to turn a few over to bring others in he has got some great assets there."
* More thoughts from Harry on this and other matters on RealAudio.