Henman, who elected to forsake the slow clay courts of Bournemouth for the medium-paced concrete of Uzbekistan, defeated Marc Rosset, the 1992 Olympic champion, 7-6, 6-4.
"Not wishing to gloat," David Felgate, Henman's coach said, "but Tim did take a bit of flak for coming here instead of playing in Bournemouth. Would he have won the title there against proven clay-courters like Mantilla and Moya?''
It was Henman's fourth final of the year. He defeated Moya in Sydney in January, having lost to Jim Courier in Qatar along the way, and was beaten by Rosset in Antwerp in February.
"Once I settled down I got in a rhythm, and mentally I was a lot stronger than when I played him in Antwerp," Henman said. "Even if I'd lost in the first round and played badly I still think I was right not to play at Bournemouth. I don't think I would have won a tournament on clay at this time of the year.''
In spite of his success yesterday, Henman will stay at No 20 in the world as a consequence of Albert Costa's victory at the Marbella Open, which safeguarded the ranking points the Spaniard won at Bournemouth last year.
Henman, who won pounds 35,000, recovered from 2-0 down in the opening set and clinched the tie-break, 7-2, winning the last five points in a row. He broke Rosset for 3-2 in the second set, after which there was little chance that the tall, big-serving Swiss would extend the contest beyond two sets.
Brits on Tour has ceased to be a jocular aside on the tennis circuit. We arrived on the south coast of England from New York, where Greg Rusedski played in the final of the United States Open last Sunday, to witness the Canadian-born British No 1 crack the world's top 10 here.
As Henman said yesterday, "We're on the up. Greg had a great two weeks at the US Open and another at Bournemouth. Now I have gone out and won a tournament. We're vying with each other.
"It doesn't depress me that my ranking hasn't improved. The important thing is that I have won another title. There are now points in the bank, and I will go up again in the next couple of weeks.
"Greg's top at the moment, but I'm aiming to overtake him soon. With the indoor season coming up, which is a good time for both of us, things are very positive.''
Rusedski's campaign was ended by Moya in Saturday's semi-finals, 6-2, 6-2. Moya, the No 1 seed, lost by the same score against Mantilla, the No 2 seed.
The third-seeded Rusedski said: "I was down to empty, mentally and physically. I hit the wall, as they say. It was bound to happen sooner or later. Carlos Moya is an excellent clay court player. If you're not 100 per cent sharp when you play him on a slow clay court, you're not going to have a chance. Even if I was fresh, it would have been a difficult match for me.''
What had he learned from the past three weeks? "I think competing is a big part. Even though I lost 6-2, 6-2 here, I still didn't give up in the match. I tried to find a way back, but Carlos was too good.
"I still have to work on things, there's no question. Once I do all that work, and keep on working, I think I can keep on rising higher and higher. That's the key to tennis really, just day in, day out work. I mean, when Lendl was No 1, he kept on working. He worked on his topspin backhand, he worked on his volley, he worked on his serve.''
Rusedski's backhand has improved immensely. "It still needs work. Some days it's very good and other days it's average, and some days it's below average.''
Is he likely to be taken by surprise finding himself on a fast indoor carpet court after the slow clay here and the medium-paced concrete at Flushing Meadow?
"No, that's going to be nice. I don't think I'll have a surprise when I hit an ace and it doesn't come back with a slice. I think I'll be pleased. Going into quick, indoor surfaces is going to be very good.
"It's a different mental demand on you, because it's quick points, and you have to make a passing shot here or there to a match, while on clay it's a mental mindset where you're going to have to get used to hitting five or six balls to set up the point to come into the net.''
His immediate plans? "I'm going to go to bed for a day and a half, celebrate for a day and a half, go to bed for a day and a half, then get ready for the Grand Slam Cup."