With just 270 pupils she does not think that St Clement's and St John's Church of England infants, Bournemouth, has enough money to increase her pound;33,480 salary.
But even if it did, she says it would be unable to give her a pay rise because of the need to maintain pay differentials with the school's leadership team, paid according to pupil numbers.
Nevertheless Mrs Palmer's position as an AST means she provides expertise to neighbouring primaries, where she would be earning more for the same job. She says her situation is unfair.
"I think I have got the short straw, I really do, considering the outreach work I do," Mrs Palmer said.
"As an infants teacher I am probably at the bottom of the AST pile but it is simply because of the size of the school, not the work I am doing."
Kevin Fitzsimmons, one of the highest paid ASTs in the country, is sympathetic to her plight.
The English teacher at Andrew Marvell school, in Hull, is reluctant to reveal his salary. But before being made an AST in April 2003 he was being paid more than pound;39,000. Promotion that month led to a further rise.
He believes the discrepancy is unfair and should be ironed out, providing it means a rise in primary pay rather than a cut in secondary salaries.
He puts it down to inherent differences in the primary and secondary staffing structure.
More than a quarter of his salary prior to becoming an AST came from five management allowance points. But primary teachers have little chance of similar increases, he said.
"You should be paid as an AST according to your experience rather than the management points you used to have," he said. "I really believe that primary teachers are over worked and underpaid."