The universities and science minister has released a pamphlet marking the 50th anniversary of the Robbins report, which paved the way for a huge expansion of UK university places.
In Robbins Revisited: Bigger and Better Higher Education, published by the Social Market Foundation thinktank, Mr Willetts says: “We are currently in the middle of a ten-year period of decline in the size of the young English population, with the number of 18-20 year olds expected to continue to fall until 2020.”
However, because of a new baby boom starting at the turn of the millennium, the 18 to 20 year-old population is set to grow from 2021 and should be almost 200,000 higher in 2035 than in 2011, he predicts.
Mr Willetts then explores a number of ways to predict the likely number of higher education students by 2020 and 2035.
Assuming social groups go to university in similar proportions as at present, and also accounting for a slight growth in the number of youngsters from more advantaged social backgrounds, the number of entrants in 2020 would be 330,000, down from 368,000 in 2011.
By 2035, entrant numbers would have grown to 410,000, Mr Willetts calculates, a 12 per cent increase on 2011 numbers.
But he also looks at numbers if “unmet demand” – students who would like to go to university but fail to get a place – were filled.
Around 50,000 students today fall into this category, he acknowledges, and if unmet demand were fulfilled, 460,000 entrants would go to university in 2035.
Mr Willetts also bemoans what he sees as an excessive focus on research.
“Looking back we will wonder how the higher education system was ever allowed to become so lopsided away from teaching,” he says.
But he argues that coalition reforms, which are partly designed to stimulate competition between universities for students, are changing this balance.
“Teaching and academic feedback are increasingly moving centre stage where they belong,” he says.