Switched back to fences the Simon Munir- and Isaac Soude-owned gelding took a decisive step forward from his comeback as he found plenty to take the Listed prize by five lengths from the running-on Black Corton.
Henderson said of the 6-4 favourite: “He is very special. Simon and Isaac haven’t had the greatest run recently, but when you’ve got a horse like this you always know he will get you out of trouble.
“He was very sick before Christmas, only because he reacted to a flu vaccination. Ascot brought him on nicely, and there we go.
“Knowing how much pace there was here, two and a half miles around Kempton – I could easily see his little feet scampering along. They turned into the back straight, picked up the bridle and always had them covered off a right good pace.
“He hasn’t got the scope of other horses and he has his own way of doing it, but he is brave as well. He has been a wonderful servant.
“If you had a straw poll in the yard he would come out number one. Everyone loves him. I know there is Altior, Might Bite and Buveur D'Air, who might be better horses, but there is not a nicer horse in the place.”
RaceBets gave Top Notch a 9-1 from 20-1 quote for the Ryanair Chase at Cheltenham in March.
Looking to future plans, Henderson said: “We were thinking Ascot Chase, then the Ryanair. That is the obvious road.”
She said: “I’m chuffed to bits. Like I said the other day, we were coming here as a confidence booster after the Ladbrokes Trophy and that is exactly what he has done.
“The trip pushed his gears the whole way, but what I loved to see was that he jumped under pressure. He travelled and stayed on all the way for me.”
The 20-year-old spent most of last year on the sidelines with a back injury and continued to make up for lost time after triumphing in the Listed contest aboard the 16-1 shot.
Son of former champion jockey Jonjo O'Neill, the 5lb claimer bided his time before forging the Jennie Candlish-trained six-year-old on late in the two-mile-five-furlong contest, crossing the line a length and a half clear of Solomon Grey.
The winning rider said: “It is amazing, really, as you are dreaming of these sort of things when you are off for eight months on the sidelines. To ride a nice winner like this means everything.
“I was always confident on him. He travelled really well and jumped unbelievable and every position I put him in he answered my call straight away. He made it very easy for me.”
He added: “I’m trying to be my own self and I want to be a jockey. I take advice and he (O’Neill senior) is very supportive and a big help, but I am my own man – even though I’ve the same name I’m very much different!”
Connections of the 16-1 winner hinted a trip to Aintree could be on the agenda later in the season, should the ground be in his favour.
To ride a nice winner like this means everythingAssistant trainer Alan O’Keeffe said: “It is nice to get a big one like that. Jennie has done a great job with the horse. He has had a few problems, his wind was one.“We’ve not had a lot of runners recently, as they want proper soft ground, but this one doesn’t. I just thought we rarely get a Lanzarote run on ground like that and he loves that ground.“He got a great ride and this lad (O’Neill) is going places. It is great for the yard to come down here and get one like that.“He will have a little break, but his future lies chasing. We won’t give him an overly-long break and we will look at Aintree.”