"It is because it's not worn, and better is the belt. This for a Batman collector is actually a really big field, but it is very niche.
"But the suit wins through, doesn't it really I mean it presents so well.
"It's so colourful and then the attributions Jack Nicholson as well."
After discovering the truth, Fiona was left open-mouthed when Steve explained the suit could fetch between £100,000 and £150,000 at auction.
Antiques Roadshow airs on Sunday at 8pm on BBC Two.
Get CyberSEO Pro (https://www.cyberseo.net/) - all-in-one content import plugin for WordPress.