In the first instance, we would suggest that you contact the local police station where the crime was reported, using the details supplied in the original post, After that, if the victim of the theft has given their details, then contact them. Once you’ve informed the authorities and possibly, the victim, then please post the details of the sighting and action taken on the relevant stolen vehicle thread. If you do not have the contact details to hand when you spot the stolen vehicle, then please call the Police non emergency number 101 or Crimestoppers on 0800 555 111
As tempting as it may be, please do not take the law into your own hands!