Allotment Fruit tree

I am the tenant of Allotment 17 - Lyncombe Hill Farm. We have been resident on this allotment for over 5 years now. I am writing with concern regarding a fruit tree on the plot next to us. There is an Elder Tree on the adjacent plot -18, which is becoming increasingly difficult to manage. It has been cut back several times but it is now well over 3m wide and high during summer with encroachment across the path and causing significant shade to our allotment as well as consumption of water. I note the allotment rules regarding fruit tress in the hand book and feel this tree now contravenes both its location to the path and its size. The lady who had tenancy of the plot did try to prune it when we asked but it really has become too big for her to manage. I am keen to write to you now as I have been informed by other allotment holders that she was going to consider ending her tenancy. I enclose photos of the tree. Unfortunately the tenant made it quite clear to us that she would never remove the tree so we feel we have no other option but to escalate this to ask if there is something that can be done ?