Capital Gains Tax on Scottish Widows Bond

I fully cashed in a Scottish Widows Bond this tax year (2024/2025). The bond was opened with £1,000 in 1987. I fully surrendered it for £6,364. I assume that there will be capital gains tax to pay. I calculate that 10% would be payable as a basic income tax rate payer. The taxable gain would be £5,364 capital gain - £3,000 allowance or £2,364 x 10% = £236.40. I was sent a chargeable gain certificate by Scottish Widows and this quoted income tax liability of 20% and did not mention capital gains tax at all? I called Scottish Widows and they said that these certificates are automated and it would best to contact HMRC re the tax liability. My instinct tells me this is a capital gains tax and not an income tax event as I fully sold the bond (consisting of fund units) and made a "gain" on this sale. Can somebody please confirm this? Thanks.

Hi,
Please refer to HS320 Gains on UK life insurance policies (2024)
Thank you.

I have spoken since posting this with a representative from HMRC. He went into great detail telling me that as a basic rate taxpayer, I will have no tax to pay. This is a UK bond with a UK company and they will have paid the basic rate of income tax over the 37 years the bond was in force. As such, there is no tax for me to pay at all. If I were in the higher income tax bracket, then there would be tax to pay. He pointed out the relevant parts of the self-assessment form that I will need to complete. As such this post can be considered closed. Thanks for your help.