Each and every council have their own set of rules for allotments. Some allow bonfires, some don't.
Some allow sheds, some don't. Some allow dogs, some allow hosepipes, some allow trees. The list goes on and on.
The one constant in all of this, is that you have to sign a contract agreeing to these conditions to get an allotment. If you don't agree with it, don't sign it.
If you can get away with anything, then that's fine while the goings good, but if the council decide to implement the rules, there is not a lot you can do.
Perhaps the answer is to have a national set of rules for all allotment sites

Cheers PJ.
I'm just off down the greenhouse. I won't be long...........