Late answer on this topic but wanted to share my thought and recent experience on that!

I don't think using an expired but extended ID card would work I'm afraid, and clearly you shouldn't take the gamble! In essence, the UK haven't acknowledged this tricky decree from 2014 so don't rely on it to cross the border.

I've recently faced an issue with the UK Home Office when trying to gain permanent residency after having spent 8 years in the UK. I had provided my expired French ID card (expired in 2015) along with my application following a recent chat with the French Consulate in London, who had confirmed UK authorities are aware of the 5 years extension when I asked for a new French ID card.

Guess what, my application has been rejected and I'm about to pay another £65 fee to reapply.

My advise is to ALWAYS use a valid ID card according to the expiry date printed onto it when travelling outside France, and NEVER assume foreign immigration services to be aware of such a validity extension

Late answer on this topic but wanted to share my thought and recent experience on that!

I don't think using an expired but extended ID card would work I'm afraid, and clearly you shouldn't take the gamble! In essence, the UK haven't acknowledged this tricky decree from 2014 so don't rely on it to cross the border.

I've recently faced an issue with the UK Home Office when trying to gain permanent residency after having spent 8 years in the UK. I had provided my expired French ID card (expired in 2015) along with my application following a recent chat with the French Consulate in London, who had confirmed UK authorities are aware of the 5 years extension when I asked for a new French ID card.

Guess what, my application has been rejected and I'm about to pay another £65 fee to reapply.

My advice is to ALWAYS use a valid ID card according to the expiry date printed onto it when travelling outside France, and NEVER assume foreign immigration services to be aware of such a validity extension.