I can confirm that you will lose your personal allowance if you make chargeable event gains of £209,000 in the current tax year as your "adjusted net income" will exceed £122,000. Take a look here and here for more information on that. Whilst the first link doesn't specifically mention the type of gain you have, the second does. I've also put a large chargeable event gain into my own tax return and that confirms what I've said here. The only way you can avoid losing your personal allowance is to spread the gains over more than one tax year I'm afraid.
I hope thsi helps but let me know if you have any further questions.
You lose £1 of the personal allowance for every £2 of income over £100,000 so its a gradual clawback. The personal allowance is £11,000 for 2016/17.
Let me just check something and I'll get back to you in a bit.
You need to keep your gross income at £100,000 or less for 2016/17 if you want to retain all your personal allowance. You say your income is £25,515 so you need to restrict your chargeable event gains to less than £75,000 in 2016/17.
Whilst the gains are top-sliced when assessing your tax liability, the gross gains are taken into account when calculating your entitlement to the personal allowance.
That would be correct so long as they are UK bonds and the gains are treated as basic rate tax paid which they will be if they are UK bonds.
You could ask just answer to do that. Alternatively, save the webpage address into an email to yourself. The question will remain open to you for as long as you like.