Looks a little small for Indurian. Sounds like a lottery replica or some sort. Write the auction company makes them look bad, more like FleaBay.
I have written to the auction house and they have not responded. I believe the size could even be correct for Indurain and it might even be one of his bikes, it is simply not a 1995 bike. This is absolutely certain. The bike looks more like perhaps a 1992 or 1993 bike when Indurain was riding Excell tubing and when Pinarello was perhaps the only manufacturer using 26 mm fork blades instead of the then more common 24 mm. These features do correspond to the auction bike. All the rest also seems to correspond with an earlier Indurain bike.
However when you are aiming at getting a thousand-fold premium on the market value of the bike due to provenance, you need to not only be close, you need to be perfectly correct. For the same £20-30K that they foresee getting for this bike, I know where one could get a confirmed and certified Eddy Merckx bike, plus a confirmed and certified Masi with original build sheet used to win a world championship in the 60's plus plus plus.
If the bike is a replica, the bike is worth less than £1K. If it is a confirmed and certified team bike from a lesser rider it might be worth £2K max. A suspected Indurain bike might also reach £2K-3K without full documents either because somebody is willing to take the risk or because they say it is still less than a modern bike that is not truly better in any appreciable way, or they have some insider information that has not yet been provided.