New Zealand trainer Tony Pike's last-minute decision to run The Bostonian in the Group One Kingsford Smith Cup proved a $420,000 bonus when the gelding scored an impressive win.

The Bostonian ($10) completed the Cup-Doomben 10,000 double when he beat Princess Posh ($151) by three quarters of a length with a short neck to Trekking ($5.50) in third.

He becomes fifth horse to complete to Kingsford Smith Cup-Doomben 10,000 double although the first to do it in reverse order.

After The Bostonian won the Group One Doomben 10,000 two weeks ago, Pike had originally planned to not start the gelding again until the Group One Stradbroke Handicap on June 8.

Pike stayed in Australia after last week's Doomben Cup meeting to watch The Bostonian work on Tuesday morning.

"His work was so good we decided to run him in the Kingsford Smith. After all it is a Group One race with $700,000 up for grabs and we have got the lion's share at $420,000 first prize," Pike said.

He said The Bostonian would now head to the Stradbroke and he hoped he would not get too big a penalty for Saturday's win.

"I hope they are kind to us and we only get a extra kilo or so," Pike said.

It is expected The Bostonian will get somewhere around 58kg.

The win continued the outstanding form of The Bostonian in Queensland as he has now won all five of his starts in the state.

"The Bostonian really seems to blossom up. David (owner Archer) and I have always intended to come back here this winter. A win in the Stradbroke would be the cream," Pike said.

Winning jockey Michael Cahill also continued his wonderful winter because he has ridden more than 20 winners in the past month.

The Bostonian's win was his third for the day after he won the Grand Prix on Fun Fact and the Premier's Cup on The Candy Man.

Cahill went to New Zealand earlier this year to ride The Bostonian to cement his relationship with Pike.

"That was a gun ride from Michael. In fact all his rides on The Bostonian were outstanding," Pike added.

Cahill said he had a lovely run on the fence behind the pace coming to the turn.

"It was just a matter of getting a run in the straight and it came quickly," he said.

The beaten jockeys had few excuses but Larry Cassidy, who rode Princess Posh, said coming to the home turn he felt she would be hard to beat but just failed.

Kerrin McEvoy who rode Trekking said he hadn't been able to get on the fence and be third in the run.

"The winner ended up getting a better run than me," he said.