Am hopefully flying to U.K. and am only taking hand luggage. Just want to ask how strict are they on the size of see thro. bag for odds. It states 20 cm X 20 cm and re-seal-able. I have looked everywhere for that size and no luck. Any ideas where to get them. All help please

I have never seen the plastic bag described as "20cm×20cm". I am used to it being called a one litre bag.

It often depends on the airline. Not a clue about Ryan Air.
We're used to Easy Jet here from Bilbao; normally, a hand luggage suitcase will include a ladies handbag; ie you need to leave room in your hand luggage case to put the handbag in, if asked to do so at the gate, which sometimes depends on how strict they are.
To get round this, we usually take a plastic "duty free" bag in which you could put a hand bag and other things, after the security check, that might not otherwise have all fitted into your hand luggage.
Hope that is clear!

Catsndogs is talking about the resealable plastic bag for cosmetics and toiletries.

I think that the same sort of bag is now also being recommended for computer, phone, and table charger and data cords, etc.

Use one of the small supermarket re-sealable food storage bags

That's exactly what you're supposed to use - the 1 lite size.

If you go to the Easy Jet site it just states 20 cm x 20 cm not a litre bag.
Still doesn't help that I cannot find a litre or 20 cm seal-able bags, but thanks for replies

Have you looked in your local supermarket near the foil, cling film, and grease proof paper?

Most of the major supermarkets sell the re-sealable bags in different sizes. Ours measure 20cm x 18cm - as near as matters the size you are looking for. I doubt anyone is going to get a ruler out and measure the bag.

Everytime we have been in the check in queue (where the signs are that tell you what you are allowed to take through) there have always been plastic bags available on side tables along the way.

This year I've flown with Thomas Cook, Easyjet and BA and just use ziplock bags, never been questioned on the size.

I also use supermarket ziplock bags but if you look in those Todo Cien / Euro Bazar type shops you can often find a little transparent plastic bag together with small containers to transfer your own liquids to. Again they might not be exactly 20x20 but that's a maximum anyway as far as I understand it.

To be clear a "Ziplock", or similar resealeable food bag is exactly what airport security expect passengers to use when they are told to put their cosmetics and cables in "resealable transparent bags".

Having passed through Luton airport on one occasion where one of their security staff was measuring the bags people were using - and then directing them to Luton's own brand which only cost £1 for two!! - subsequently the CAA changed the wording of the requirement and it now says" measures approximately 20cm x 20cm "

Same happened to me at Manchester - had my stuff in a small plastic bag and told to go and buy another one from a conveniently-placed vending machine