Technically, according to English real estate law, any *attachment* to the real estate does become property of the owner. This does not include any freestanding equipment. After the lease expiration. However, if the tenant returns the property in the same condition as it was when it was leased, they would be hard pressed to make any kind of case against NWBO.
Also, the terms of the lease is so long, that the actual value of the improvements will have been depreciated to almost nothing by the time the lease expires.
For all practical purposes, NWBO continues to own their improvements.
You need to give up this line of thinking, as it is silly