At present the UK Government is saying…

 

‘Phones, laptops and tablets larger than 16.0cm x 9.3cm x 1.5cm will not be allowed in the cabin on ‘direct’ flights to the UK from Turkey, Lebanon, Egypt, Saudi Arabia, Jordan and Tunisia only’

 

To clarify- It does not affect departures from the UK and arriving flights from other countries. It also means you can still travel on these routes, but these larger electronic items must go in checked luggage, although you will need to seen if your insurance will cover them when travelling in the hold?

 

https://www.gov.uk/government/speeches/additional-airline-security-measures-on-some-routes-travelling-to-the-uk