It's not right,the tags should stay on the car and v5 sent off by yourself or the scrapyard who processed the car,end of no ifs buts or maybes as selling the v5 and I.d serves no legal purpose.
But there's always the replica that can be made real or a q plater needing a clean I.d or the low life's needing it to ring a car.
My pal had 2 s2's bitd,I seen the second 1 and immediately recognised the reg but not the car,I ended up buying it for buttons as the big ends were gone,only a while later did I figure out the reg had been on a pals white s2 that got written off which I bought a lot of parts from only now it was on a very early grey s2.
Turns out a satans slave member wanted it disposed of by a shady guy,he took it and rung it the sold it to my pal.
I drove it for a year with a shagged engine then broke it,I kept the number plate but sent the v5 to dvla saying it had been scrapped.
Wasn't good knowing it wasn't right but knowing it wasn't stolen made it less worrying.