I'll try to assist if I can.
s.3(4) provides for local authorities to take action over littering - essentially it gives the the power to draft their own littering policy and enforce it 'with a view to promoting the abatement of litter.' All s.4(3) does is enable local authorities to publicise the offence and take action themselves in the event of littering. It enables them to take action on their own account rather than rely on the police to do so.
This is extremely common in national legislation, for instance the granting of powers to local authorities to create their own alcohol-free zones under bylaws and enforce them themselves/with the assistance of police.
The reason for the prosecution citing s.3(4) is to justify enforcement by the local authority and further may refer to local bylaws that they have enacted themselves.
You're absolutely correct that it looks a little clumsy and for preference the summons should cite s.3(4) and s.3(1) in conjunction to ensure clarity.
However, I don't believe that any appeal on the nature of the summons would find much favour with an appeal court as the nature of the offence was presumably made pretty clear in the witness statements etc.
You are entitled to appeal this conviction if you choose to - you need to ensure that you file the notice of appeal with the appeal court, court of conviction and prosecuting authority within 21 days and thereafter you'll be notified of the date of appeal.
I hope that assists but please feel free to ask any follow up questions that occur.
Edited by Simon on 2/7/2011 at 9:44 AM EST