Wasn't sure whether to post this here or on the Airline forum, but since it does involving flying to and from the UK, I thought someone could advise me. I just bought a rolling laptop case that is 15.25"x 10.75"x14.75". Is that too big to bring through security?

The crucial rule here is what you can take through UK security on your return.

This ISN'T being punctiliously enforced, but it's 56cm x 45cm x 25cm.

Which in theory is bigger than the dimensions you quote - though only you know whether your dimensions include the wheels and handle or not.

If you hit a fussy checker, the whole case - and anything else you're carrying - must fit inside the 56cm x 45cm x 25cm box.

it does inlcude wheels and handle. My concern is that according the algorithim of .39"=1CM 10.75"=27.56CM. Not sure if it would fit since being over technically 2CM. I know this sounds dumb, but have not travelled overseas since everything changed in August

Everything didn't change in August.

The reality is that for a couple of weeks, Britain rigorously enforced some very draconian rules. Those rules have been relaxed twice since - and the system is also more relaxed about enforcing them.

You're right that my maths are wrong - and there's always the chance that another scare like this afternoon's will get everyone all fussy again.

But surely most laptop cases will squeeze a bit anyway? There ought to be enough squishiness to save that extra inch.

What happened this afternoon?

You mean in Heathrow T2 ?
A man dropped a bag in front of a checkin counter (Air Algeria) and run away.
The terminal was evacuated and the bomb squad called.
The bag didn't countain any bomb and the man was arrested later.
Traffic has resumed

http://news.bbc.co.uk/1/hi/uk/6038082.stm

The sizes of

56 centimetres long (approximately 22 inches)
45 centimetres high (approximately 17.5 inches)
25 centimetres deep (approximately 9.85 inches).

are the international standard sizes, therefore it's not just Heathrow you've got to worry about.

I'd just take something out of the laptop bag to make it thinner

"Anyone travelling from Heathrow is advised to check with their airline." - BBC

Let's see: 93,150* passengers all checking with their airlines...

*(68 million passengers per year divided by 365 days divided by two - departures only.)

I am going flying in and out of LGW. Any chance more restrictive than LHR

The same rules apply to all UK airports