Aer Lingus to Gatwick via Dublin?

Its NOT CUSTOMS you go through, its Immigration.

Ireland is a different country than England.

Ireland is NOT part of the United Kingdom.

Never taken your flight but speculating you’ll have to go through immigration twice.

Hopefully someone else HAS taken your flights and can answer from experience.

" NOT CUSTOMS you go through, its Immigration.
Ireland is a different country than England.
Ireland is NOT part of the United Kingdom.
Never taken your flight but speculating you’ll have to go through immigration twice. "

Ireland and the UK share the same Common Travel Area, therefore when ones enters Ireland one enters the UK too and vice versa. The OP will pass immigration and leave airside in Dublin and thier onward flight is a domestic one.

One will have to show ID for that flight for security reasons - however, not immigration purposes.

I've flown between Ireland and the UK numerous times. No immigration when flying from Ireland to the UK

However, unless you travel on a UK or Irish passport, you will go through immigration in Ireland when flying FROM the UK.

If you fly back to the US via Dublin, you will go through US immigration in Dublin.

You will go through a form of border inspection but perhaps not as thorough as when you enter Ireland. I believe they're only checking you don't need a transit visa.

"You will go through a form of border inspection but perhaps not as thorough as when you enter Ireland. I believe they're only checking you don't need a transit visa. "

Its a domestic arrival at LGW there is no immigration or 'border inspection'.

Thank you for your replies. I appreciate the good help.

Good intel.

I have flown perhaps half a dozen times from Ireland to the UK (three different airports.) No one checked anything.

However, there is one difference. When you fly directly into the UK, you are given six months stay for tourist purposes. When you enter the UK from Ireland, you only get three months.

This website might help you with flight connections:

https://www.dublinairport.com/flight-information/connections

Thank you, Frank II, for the additional information. I appreciate all the input from everyone. Most helpful.