What a guide price actually is
A guide price at a UK property auction is not a valuation. It's the auctioneer's estimate of where bidding will open, set deliberately low to draw interest. Reserve prices — the figure the seller will actually accept — typically sit 10–15% above the guide, sometimes more. Treat the guide price as marketing, not evidence of value.
Why auctions produce genuine BMV, and why they don't always
Auction lots are disproportionately repossessions, probate sales, and properties with title or condition issues a mortgage lender won't touch — all situations that create real, structural discounts rather than marketing spin. But auction houses also know this reputation sells tickets, and "guide price" framing can make an ordinary property look like a bargain when it isn't one.
How to actually value a lot before bidding
Ignore the guide price entirely when underwriting a deal. Pull recent sold prices for genuinely comparable properties on the same street or postcode sector — condition, tenure, bedroom count and any recent refurbishment all matter. This is exactly the comparison PropertyAlert's postcode benchmarking is built around: real Land Registry sold prices for the sector, not asking prices or guide prices from a portal.
Cost-stack before you bid, not after
A lot that clears at 20% under your comparable-value estimate isn't necessarily a 20% discount once you add the auction buyer's premium, legal pack review, stamp duty, any required refurbishment, and finance costs during the process. Deduct all of it before deciding your maximum bid — not after you've already won the lot.
Before you bid
Always have a solicitor review the legal pack in full — auction packs routinely contain restrictive covenants, unresolved boundary disputes, or arrears that don't show up in the listing photos. A cash-only requirement or a very short completion deadline is often the real reason a property is cheap; make sure you can actually meet it before you raise your paddle.