Signs on roundabouts

[Business Man]

On some roundabout islands i've noticed signs which say left turn on them. ( The blue circle with the white arrow pointing left ) but yet i see drivers go straight on.

Can someone explain these signs as i cant see anything in the highway code unless i've missed it somewhere.

Say your approaching a roundabout from the south which as only two exits, left and straight on. you see the sign which says "left turn" should you only take the first exit or can you go straight on ?

 

[Business Man]

Ahh well that explains it then lol

 

[Business Man]

no ive only seen the signs on a few roundabouts.. they just seem to be on a selected few. actually there isnt any near to me. i was just curious what they meant as i thought maybe it was telling drivers to exit left. I thought it was common knowledge you go clockwise round a roundabout anyway. I suppose they're just there to warn foreigners or people with alzheimer's incase they forget