If the value of the FTSE affects the income from your pension then I don't think you have an annuity, as these offer a fixed (and modest) return regardless.
If you took 25% of your pension as cash then I imagine the remainder is in drawdown:
...in which case it will be invested in funds/trusts/stocks/bonds etc. If it's being managed by someone else then it may be on a platform which does not offer all possible investments - perhaps just funds (and less frequently, investment trusts) - rather than individual stocks. You'll have to talk to your IFA or platform provider. I have a feeling that you would have to switch out of your current platform provider to a SIPP, which would take time and come with associated costs.
Just speculation - don't take this as financial advice because it isn't.
RE: A company with potential but will it be realised30 May 2021 18:43
The original Betamax tapes only ran for an hour so not great for recording a film. The lesson being that the short duration option is never the best one.