The article states the following:
More than 21,000 new homes are being earmarked for the town and surrounding area over the next 20 years and the council said two upper schools and one grammar "might be required".
New homes are being built now, but NOT the 21,000 on which this article is based, nor the claims of the councillor demanding 3 new schools.
Were the article based on a need for new schools due to the level of currently agreed development I would have no argument with the discussion. However, it is not, as the article goes on to make clear:
"We are at the very early stages of the planning process and much will depend on what type of housing developers apply to build in future, and subsequent requirements for school places as a result."