Whether particular activities are conducted in such a way as to
amount to a trade is essentially a question of fact. There is
detailed guidance at
BIM20050 onwards. At the margin the
issue can call for fine judgement.
The insurer will have been authorised under the Insurance
Companies Act 1982 Section 3(1) to carry on business. It seems
unlikely that such business will be conducted in such a way as not
to amount to a trade. But you will need to establish the facts in
each case and confirm the position.