British tender coins minted in 1837 or later years have unique appeal to the knowledgeable investor- they are exempt from Capital Gains Tax (CGT) .
Extract from HMRC Capital Gains Tax Advice on Currency
Capital Gains Tax is a tax on the profit when you sell (or ‘dispose of’) something (an ‘asset’) that’s increased in value. It’s the gain you make that’s taxed, not the amount of money you receive.
CG78307 – Foreign currency: coins: legal tender
Coins are to be regarded as currency only if they are legal tender at the time of their acquisition or disposal. Coins which are currency but not sterling, for example Krugerrands, are chargeable assets.
CG78308 – Foreign currency: coins: legal tender
Sovereigns minted in 1837 and later years and Britannia gold coins are currency but, like all sterling currency, are exempt because of TCGA92/S21 (1)(b).
Further general info related to Capital Gains Tax available at http://www.hmrc.gov.uk/manuals/cgmanual/Index.htm