"...The law on scattering ashes in the UK is fairly relaxed. You can even scatter or bury ashes in your garden if you wish. There is nothing explicit in the legislation to restrict people in disposing of cremated ashes. "
http://www.scattering-ashes.co.uk/help-advice/law/

 
"Many organisations state that they do not allow scattering for environmental reasons. Cremated ashes are rich in calcium and phosphorus that can affect alkalinity and act as a fertiliser. It depends upon the frequency of the scattering and the sensitivity of the environment as large amounts of ashes scattered in a sensitive environment will, in time, have an impact. However, we have found no evidence to suggest that occasional scattering in ordinary environments, such as a field or beach, is likely to cause any demonstrable negative impact."
http://coffincompany.co.uk/wheretoscat 

Watch which way the wind is blowing.
Maccoll's line always makes me wonder what he had in mind:
"...Take me to some high place
of heather, rock and ling;
Scatter my dust and ashes,
feed me to the wind.
... I'll be riding the gentle wind
that blows through your hair,..."