To chance taking DS abroad without permission

[Marmight]

Arranged and booked for a 2 day stay in a European capital as a birthday treat for my teenage DS.
ExDP is refusing to either sign a letter to give me a permission or giving a reason for his refusal.
Trip is around 10 days away.
DS is obviously upset and it has been pointed out to ExDP it's not stopping me going, just his DS.
I don't think I have time to get a court order in place as its not an urgent case, even though it is time dependent.
I have taken DC abroad before with his permission. (Other DC is staying with ExDP for this trip)
AIBU to chance it without explicit permission??

My eldest son has a different surname from me and is not my dh's son. We go abroad twice a year. I bring his birth cert with me but no official letter from his dad. Its never been a problem. Once border control asked him who I was and he said 'my mum'. Never been asked if I have permission from his dad. He's 12 now....we are only just back from a spring break where again we weren't questioned.

I have 3 children , all have my name, I've travelled holidays to Europe with them most years and never been asked for any letter. We barely get glanced at through passport control. I've not even thought of getting a letter (first time I heard of it was on mumsnet , I didn't even know that was technically a thing).

Just to update...

I saw a solicitor who advised a specific issue order. I did all the leg work for the application.

I got my court order yesterday to allow my trip to proceed, all within 4 working days of the application being made to the court.

He didn't show up at court to argue his case.

I've also submitted a child arrangement order application to name me as the resident parent. This will mean that I no longer have to ask specific permission for each trip in the future as long as it's not longer than 28 days outside of the UK.

Brilliant update. Have a great trip!

A major flaw with the permission thing is when the nr parent isn’t in the life at all. Who are they supposed
To get a letter from and how are staff to know whether the parent is lying or not.

I’ve taken mine out loads and getting consent isn’t an option.

What age is this up to? 16 or 18? The UK Gov link says to find out what the age limit is in the country you are travelling to, but doesn't seem to set out what age the UK means by it!

Glad it's resolved!