A bit of devils advocate here …
Allotments are generally owned by the local authority and rented to individuals. Bye laws etc re the rental agreement cover what individuals can do. I am sure the allotment association also has rules.
The problem arises when the ‘public’ are invited to an ‘event’ there.
Risk assessments are merely a simple means of covering backs in case of litigation, to show you have considered additional risks for the event, and taken reasonable steps to either eliminate or reduce them. ie a huge BBQ for 200 people. If people are paying admission they have a right to expect reasonable safety.
Before anyone gets fired up, R.A.’s only take minutes to write. Three columns. Single page. Identify a genuine hazard (calor gas fire, trip hazard), who is likely to be affected, and what you have done to eliminate or reduce the risk. Sign and CC it to the local authority.
By all means flame me, but if the rubber gas pipe on the BBQ catches fire and there is an explosion which injures people at a 'paying event' . . .
It is just old fashioned common sense, the only difference is that you have written down what should be ‘obvious’ beforehand.