Tax on foreign pension accumulated prior to becoming resident.

I have a pension that I invested in prior to becoming tax resident in the UK. The pension was invested in 1994 - 2008 in foreign country. I became a tax resident in the UK in 2008. I would like to withdraw the pension from foreign country and bring to the UK in the 2024/25 tax year. Will all of this be taxed or only the portion since becoming tax resident in the UK i.e. 16/30 years portion taxed in the UK with 14/30 not liable to UK tax?

Hi,
The answer to your question will depend on the tax treaty (if there is one) between the UK and the country in question.  
Please have a look at the treaties at Tax treaties and search for an article relating to pensions.
Thank you.