If it's on the DVLA database in your name (i.e. it has a V5 whatever it is now), and it's not SORNed, and it's not on the insurance database you'll be fined.
In the meantime, all the criminals (you know, those people who, by definition, are not bothered about obeying the law) will continue to drive uninsured and untaxed vehicles that aren't registered in their name.
Another brilliant f***ing way to fine the law-abiding who forget to fill in a form, while the people they are trying to stop carry on exactly as before.
Oh, and compulsory registration of ALL vehicles, including competition cars and bikes, was mooted a few years ago, but didn't become law.