Pendleton saddles her first winner.
The two-time Olympic cycling champion was unshipped from Paul Nicholls' charge on her first start under National Hunt Rules at Fakenham just under two weeks ago, but the duo made no mistake this time.
Sharply away, Pendleton survived a couple of sticky leaps to triumph aboard the 5-4 favourite, running out a 29-length victor.
Pendleton was positive from off, having tried to come from behind at Fakenham, and got her mount to the front from the beginning.
Her task was somewhat eased when Gauvain, who looked a likely rival, crashed out at the sixth, but Pendleton herself had to survive a slightly shaky jump at the eighth as well as a slow leap at the 10th.
However, she managed to get Pacha Du Polder back on an even keel before kicking for home with two to jump.
She negotiated both of those obstacles with the minimum of fuss, cruising home from Big Fella Thanks to a warm reception from the Wincanton crowd.
Pendleton said: "It was fantastic. I really just wanted a good round.
"I wanted to get round on the horse and give him a ride he deserved because he's Pacha Du Polder and he is a lovely horse. I feel very honoured and lucky to be allowed to ride such a wonderful animal. I was very frustrated (after Fakenham) but also I know that this sport is full of thrills and spills - that can happen, it's racing.
"When I started this challenge, people said, 'You know you're going to fall off, don't you?' and I said, 'Yes, I know', but it's a very small price to pay for the joy you get in riding a thoroughbred racehorse."
Pendleton now faces a crucial few days with her support team, which includes Nicholls and jumping guru Yogi Breisner as well as Lawney and Alan Hill, from whose yard she has been riding out, set to discuss her ultimate aim of riding at the Cheltenham Festival.
The long-term ambition for Pendleton was to ride in the St James's Place Foxhunter Chase at the main meeting later this month and her team will now assess the viability of her once again partnering Pacha Du Polder in the amateur equivalent of the Cheltenham Gold Cup.
An announcement on her participation is expected on Monday.
Pendleton said: "I will be doing some point to points (this weekend) and then I'll see what the experts around me decide and I'll go with their choice. I'll still be riding the rest of the season." Nicholls was impressed with Pendleton's effort and believes that performance qualifies her to take her place at Cheltenham.
"That was good, I liked the way she did the job. It really was a nice ride and she will have learnt a lot from that," said the Ditcheat handler.
"She did a good job schooling at home on Monday "Hindsight is a wonderful thing and maybe we should have bowled along at Fakenham, but I was just concious that if we get to Cheltenham, we couldn't ride him like that. This is a tricky course and she did well in that wind. She looked a completely different rider "We will all get together to make a decision. There is nothing to say she shouldn't line up and on today's performance she is more than qualified in my book to ride.
"Since that schooling session at home, the improvement she has been made has been astounding."
Coral now go 6-4 about Pendleton completing at Cheltenham as well as offering 8-1 about her finishing in the first three at Cheltenham, while Pacha Du Polder is 20-1 from 33s to win the race on March 18.
Victoria Pendleton winning on Pacha Du Polder