If I am not mistaken, yellow leads are for 110 volt power tools use only (via transformer) and therefore, I assume, not suitable for 240 volt hook up. May be wrong but am sure others will confirm.
But i had a JCB brand mower [until it died after 6 months] that came with a yellow cable to suit the branding, not very good on 'JCBs' part in light of the above.
I've kept the cable as a 240v extension lead , better hope the HSE don't see it!
Given the similarity between yellow and orange, particularly when weathered, I doubt there's any ruling on colour of the cable - the plugs/sockets must of course be blue for 230v and yellow for 110v.