Hi
Per Article 18 of the UK/Portugal Double Taxation treaty
'Remuneration or pensions paid out of public funds of the United Kingdom or Northern Ireland or of the funds of any local authority in the United Kingdom to any individual in respect of services rendered to the Government of the United Kingdom or Northern Ireland or a local authority in the United Kingdom in the discharge of functions of a governmental nature, shall be taxable only in the United Kingdom'.
Your local government pension will therefore be taxable only in the UK. As regards your UK State Pension, it will be relievable under the 'Other Income' article if 'subject to tax' in Portugal, and will therefore not be taken into account when assessing the UK tax payable on your local government pension.
Please see
UK/PORTUGAL INCOME TAX CONVENTION SIGNED 27 MARCH 1968
Thank you