Judge Barron said the circumstances of his judgment include:"The nature and extent of the enquiry with the involvement of the Electoral Commission and investigations taking place not just in South Thanet but across the country. As Louise Edwards [Head of Regulatory Compliance and Casework at the Electoral Commission] points out this is on an unprecedented scale."
[...]
"Whilst there will almost always be a public interest in investigation of offences under the Act the weight of the public interest will depend on the nature and extent of the allegations being investigated.
"In this case the allegations are far reaching and the consequences of a conviction would be of a local and national significance with the potential for election results being declared void."
The Tories are being investigated in 29 electorates. That's far more than their total majority. If elections are declared void, then the UK could very well get a new government. And if the ruling party is convicted of widespread, systematic electoral fraud, it will need one.