I always keep my VRC in the file with the insurance documents but I spent 2 hrs yday looking for a VRC for a car I am scrapping, I cannot believe that I cannot find it as my filing is system is good, or was anyway! So annoyed that I will have to get a replacement one costing 12 quid just to be destroyed and that's not even the biggest nuisance, garda has to sign form and I have to send off cheque or postal order with it! The cost and hassle of getting draft/postal order, surely in this day and age there should be an online option.
Anyway I have never been asked for VRC other than when I brought someone else's car for NCT, it's like once it's your own car they don't bother but if someone elses it's another check I presume.