Register to vote!
Click on the British government link below to start the process and build the number of British citizens registered as overseas voters into a serious constituency size ( 70,000 – 100,000).
https://www.gov.uk/register-to-vote
“Use this service to get on the electoral register or to update your details.
You need to be on the electoral register (sometimes called the ‘electoral roll’) to vote in elections and referendums.
Registering takes around 5 minutes.
You’ll need your National Insurance number (if you have one). You may also need your passport if you’re living abroad.”
Unfortunately, if you left the UK 15 years or more ago the system will reject your application.
Votes for Expat Brits blog 