Last year, 451,900 full time equivalent teachers were working in English state schools, compared with 457,000 in 2016.
In 2011, there were 440,000 teachers in English schools, reaching 449,000 by 2013, and 457,000 by 2016 - but last year the number fell sharply.
Despite a steady rise in the number of teachers entering the workforce, this has been outpaced by the increase in those leaving - with the rapid growth in the number of those quitting before reaching retirement age a particular concern.
And this classroom exodus has coincided with an increase in the number of students, leading to higher student:teacher ratios and threatening to leave schools seriously understaffed.
The crisis is particularly acute at secondary level - schools serving students aged 11 to 16. While the number of full-time equivalent secondary teachers fell 1.9% from 2016 to 2017, the number of students in this age bracket is forecast to increase by 19% over the next decade.
There are now 16.7 students to every qualified teacher at secondary level, up from 16.4 in the previous year and the highest figure in more than a decade, with every indication that that will worsen over the coming years.