Tyres going bald on outer edges. Legal or not?

Hi it's my first post so go easy on me!

I just noticed my tyres have worn all the way down on the outer edge of both front wheels. The rear tyres have 'cracking' (right word?) on the outer edges. I've attached images below to make it clearer.

I just wanna check which (if any) are not road legal. I've been checking forums etc all morning, and nothing yet has compared to the state of my tyres to make it clear whether they are within the rules are not.

[img]http://s22.postimg.org/sk9ypm1b1/Front_Driver.***[/img]
(Front Driver Side)

[img]http://s2.postimg.org/9ae9uj6qd/Front_Passenger.***[/img]
(Front Passenger Side)

[img]http://s24.postimg.org/sirr7733l/Rear_Passenger.***[/img]
(Rear Passenger Side) (Tread looks the same on both rear wheels)

Hope you can help. Cheers!