Hello and welcome to the site. Thank you for your question.Yes, you will be liable to Capital Gains tax on the gain made on selling your share of the property.As you inherited the 25% beneficial interest in the house in 1970, you would use the valuation in Mar 1982 as your cost price.Your gain would be the difference between the valuation at Mar 1982 and the value now.More information on this can be found here
You would claim annual exempt amount against this gain and the balance would be chargable to CGT at 18%, 28 % or a combination of both depending on your taxable income including the gain in the year of sale.
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