I (and several friends too) have all been pulled with a conformation email from the DVLA saying tax has been paid for and never had any trouble.

Some of those times the cars were on SORN for months too.
As stated, although it's TECHNICALLY against the law, since you can get it on line there's a lot more lee way, as long as the car comes back as being taxed. I'm guessing the law to display will change soon as it's not being enforced frpom what I've seen.

It would take a properly wanky copper and a bad attitude towards the police to get done for it.

I drove round for 3 weeks with just the confirmation email as the disc was delivered to my parents house.