The next Windrush scandal, except that everyone gets to take part
The Home Office is already trying, and failing, to implement a digital ID system for millions of foreign permanent residents living in the UK. It's called the eVisa system, and it is riddled with flaws. The campaign group the3million has recently published a detailed report on the failings of the eVisa system (https://the3million.org.uk/digital-status-crisis) which should be required reading for anyone advocating for a nationwide digital ID system.
On the plus side, given the track record of large, complex government IT projects, this one is never likely to get off the ground.