If the log book V5 is not correct, it depends why it is not correct, if it ios down to the DVLA you are not breaking the law for someone else's mistake.
Stop worrying about the plod, they would most likely not even know the difference anyway, and besides it is NOT illegal anyway.
If the log book had 1.25 on it when you sent it off, send it back with new details filled in, if it already had 1.4 on it still send it back with new details filled in.
You of course must inform your insurance company, the trouble is they may class it as modified, as it deviates from that made by FORD!!
They may then decide to load it, ie push up premium a lot, some see it this way some don't, talk to an UNDERWRITER, at your insurance co, not some numpty that does not know thier arse from thier elbow, and you will get more sense.
tabetha