Purchase of freehold - loss of development rights

Other

I am a lessee and together with 2 other lessees am negotiating the purchase of the freehold. We have agreed a price but the freeholder is also a lessee (of the basement) and wants us to grant a leaseback with extensive development rights including structural and basement development. I cannot agree as I would lose my tenant.

I have checked the law and there is no specific right to development rights but I am unsure what the LVT would consider reasonable for central London and would like to avoid the costs of the hearing if possible.

I would be grateful if you have any experience of this.

Regards