I agree with Carol. The annuity is income as it consists of regular, i.e. annual, payments fixed to a particular period, i.e that year.
Money can be income or capital both not both. There’s an old IS Commissioner’s decision about this: R(IS) 3/93 (or CIS 654 1991), which states:
“The metamorphosis [i.e the point at which income turns into capital] occurs in relation to each item of income after payment of any tax liability and after the period in respect of which the item falls to be attributed has expired.”
Which basically means that if the annuity is treated as income it cannot also count as capital until the period which it covers is over. In this case at the end of the year.