I'm in the same position too. Here are the results of my research on the subject:
As you can see by following the two links above, there are many special cases and caveats, but to summarise the main points:
- The gains are taxed as income.
- You can apply time apportioned reductions to reduce the amount of tax you need to pay if either the beneficiary (if the policy was issued after 6 April 2013) or the policyholder (if the policy was issued before 6 April 2013) was not resident in the UK for any part of the period since the policy was taken out.
In my case, as I understand it, as the policies were issued before 6 April 2013, and the policyholder was never a resident in the UK, I shouldn't have to pay any tax.
I would be glad if someone else could confirm this, or let me know if my understanding is flawed.