Sell 20p Struck on 1p Blank (Wrong Planchet Error)
Identify & value the rare 20p struck on a 1p blank. Weight, colour, authentication tips & realised auction prices (£150–£2,500+).
Typical UK collector & dealer range for circulated examples
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Zero seller fees. Insured UK courier or private London & Manchester appointment.
Market Valuation & Pricing Notes
Extremely rare off-metal error. Documented examples: 1983 bronze blank sold on eBay for £170 (2026); 1990 copper-plated steel blank (overseas territory issue) authenticated by Royal Mint Museum, sold at Tennants auction for £1,400 (2023), another estimated £1,800 (2023). Values depend heavily on year, blank type, authentication, and provenance. Graded examples (PCGS/NGC/CGS UK) command significant premiums.
Physical Authentication Checkpoints
Our specialists verify these exact specifications when appraising your 20p Struck on 1p Blank (Wrong Planchet Error):
- Weight: ~3.56 g (standard 1p weight) vs 5.0 g normal 20p
- Diameter: ~20.3 mm (1p blank) but heptagonal (Reuleaux polygon) shape from 20p collar
- Colour: Copper/bronze hue — not cupronickel silver
- Edge: Plain (no milling), consistent with 1p blank
- Obverse/Reverse: Full 20p design struck on smaller flan; design may run off edges or show partial striking
- Metal analysis: XRF/spectrographic confirmation of copper-plated steel or bronze composition
- Die alignment: Medal alignment (standard UK), check for rotation errors
- Surface: Original mint luster/strike characteristics; no tooling marks where date/denomination might have been altered
Coin Specifications
- Catalogue ID
- gb-20p-wrong-planchet-1p-blank
- Denomination
- 20p
- Issue Year
- Various (documented 1983, 1990)
- Rarity Tier
- High-Value Error
- Mintage
- Unknown (Mint Error)
- Weight
- 3.56 grams
- Metal Composition
- Copper-plated steel (1p blank) / Bronze (pre-1992 1p blank)
Common Fakes & Variant Confusion
Common fakes: normal 20p plated or coloured to mimic copper; 1p coins with 20p design artificially engraved; date-altered 2008 undated mules. Confusion with: 20p struck on 10p blank (larger, 24.5 mm, heavier ~6.5 g); 20p struck on foreign planchets (various weights/compositions). Authentication by Royal Mint Museum, PCGS, NGC, or CGS UK essential for high-value transactions.
Best Ways to Sell Your 20p Struck on 1p Blank (Wrong Planchet Error)
Compare liquidation routes in the UK, or sell directly to Finacforce with zero auction commission.
Specialist Numismatic Auction (Baldwin's, Spink, Noonans, Tennants)
Highest realised prices for authenticated errors; expert cataloguing; 15–20% seller's commission; slower timeline (months).
eBay UK (with PCGS/NGC/CGS UK slab)
Faster sale; global buyer pool; 30–50% premium for slabbed vs raw; fees ~13% + PayPal; risk of disputes on raw coins.
Coin Fairs / Dealer Purchase (e.g., A.H. Baldwin, Spink retail)
Immediate cash; no auction wait; typically 60–75% of auction hammer; limited competition.
Private Treaty via Numismatic Forums/Collectors' Clubs
No fees; direct negotiation; requires trusted counterparty; limited price discovery.
Related Coins & Valuation Guides
2011 Olympic Aquatics 50p (Lines Over Face / Withdrawn Design)
Cupronickel (75% copper, 25% nickel)
1983 'New Pence' 2p Mule
Bronze (97% copper, 2.5% zinc, 0.5% tin)
2014 Lord Kitchener £2 Mule Error (Missing 'TWO POUNDS' Denomination)
Bimetallic: Outer ring - Nickel-Brass (76% Cu, 20% Zn, 4% Ni); Inner disc - Cupro-Nickel (75% Cu, 25% Ni)
Silver 2p Wrong Planchet Error
Cupro-nickel (75% Cu, 25% Ni) or nickel-plated steel (10p planchet)
1994 Bank of England £2 Gold Proof Mule (Double Sovereign Obverse)
22-carat gold (.917 fineness)
2016/2017 Dual-Dated 12-Sided £1 (Micro-Lettering Mule)
Outer ring: Nickel-brass (70% Cu, 5.5% Ni, 24.5% Zn); Inner disc: Nickel-plated alloy