Harding, who won the Queen Mother Champion Chase on One Man in 1998, spent nearly all of his career connected to the Gordon and Nicky Richards stable in Greystoke, Cumbria.
Off Art (5-1), without a win since 2013, had hinted at a return to form last time out and got up close home to provide his in-form trainer Tim Easterby with a birthday winner.
For the last two furlongs Adrian Nicholls appeared to have everything covered on Fire Palace, with Ian Mongan on Character Onesie in there battling too.
Even Ollie Pears threatened to get involved on Detachment but his run petered out up the rail.
Harding used all his notable strength from the saddle to prevail by half a length.
Harding said: "That was hard work but it was good fun! I ride out three or four horses every day who are breakers (being broken in) but then you come and do this? I thought, 'oh my God.' No, it was good fun really.
"I am 45 in two weeks' time and I left home when I was 15, so I was a jockey for almost 30 years. It just takes a little getting away from. But I do the jockey coaching job and that keeps me a bit involved.
"Jamie Gormley is one of mine and he is a good lad and there are some cracking good jumps lads too."
Easterby said: "It's a wonderful race to be involved in, it's such a big day for racing. A lot of money is raised for charities that need it. Once racing stops, for a lot of these guys riding and working in the industry, things can happen and they need support.
"Brian's ridden plenty for me over the years so it was great to have him. A brilliant, solid jockey who always gave a horse a good ride. You never had any problems with him and you didn't have to give him orders.
"I'd like him to come and school some for us, that's for sure."