Ireland/Northern Ireland Covid test

This is the guidance for those travelling within the Common Travel Area, i.e. from Ireland to N Ireland

https://www.nidirect.gov.uk/articles/coronavirus-covid-19-travelling-within-common-travel-area

• If you're travelling from within the Common Travel Area (CTA) and staying overnight in Northern Ireland, you should take a rapid lateral flow device test (LFD) before you begin your journey. You should only travel if the test is negative.
• You should also take an LFD test on days two and eight of your stay.
• You should not travel to Northern Ireland if you have COVID-19 symptoms, or have received a positive COVID-19 result.
• You do not need to fill in a Passenger Locator Form if you’re travelling from within the CTA and you have not been outside the CTA in the last 10 days.

Later next month I'm hoping to travel to County Down after several days in Dublin and if I understand this correctly then I should have no issues crossing the open border. I'd probably be taking a train or bus.

Then I would like to continue on to England. If I understand the current rules correctly a person who has been in the Common Travel Area for at least 10 days and is fully vaccinated should be able to enter Great Britain then without restrictions. I base this on information found on the Northern Ireland page for travel into NI from other parts of the CTA. Hopefully it works the same way from NI to GB. By that point I will have been on the island of Ireland for at least 10 days.

This is all tentative now because they could easily change the rules on us as covid rates change. The way our rates are rising in the US we could have mandatory quarantines re-imposed on us, but hopefully not. I booked my tickets on Aer Lingus and they are allowing no fee changes in flight through December 31 so it allows the traveler to be sufficiently nimble.

I guess this is my answer.

From: https://www.gov.uk/guidance/red-amber-and-green-list-rules-for-entering-england#ireland-the-uk-the-channel-islands-and-the-isle-of-man

"Ireland, the UK, the Channel Islands and the Isle of Man
You do not need to take a COVID-19 test or quarantine on arrival in England if you are travelling within the UK, Ireland, the Channel Islands and the Isle of Man, (the Common Travel Area), and you have not been outside of the Common Travel Area in the previous 10 days."

Hello, I am unvaccinated (living in Scotland, UK) and recently travelled to Northern Ireland (UK) but, I went by Ferry as I could not get a clear answer as to whether or not I would need to do PCR Tests to fly. Since NI is within the Common Travel Area, is it up to me, as an individual, to just make sure I do a lateral flow test and I am safe to fly or, do I have to pay and show proof of PCR Tests? Any advice would be great as I'm due to go over again later this month (for four days) and flying would be a whole lot more convenient! I just don't want to get to the airport, discover i haven't done something and not be able to get on the flight. Thanks!

for a domestic flight, there's no legal requirement for any tests to fly within the UK. If the airline wants anything, you need to check with them.