HMRC confirmed today - no extension to tax return deadline - fuck them.

Isn't that a little harsh?
I assume you're talking about personal income tax returns with a deadline of 31st January 2021.
These are for the tax year ended 5 April 2020. So the taxpayer will have had more than 9 months to get the figures together. If someone has left it this late, it is hardly fair to blame the government.