You can give the payment through the court as has been suggested. But you should also keep in mind the fact that your landowner has plans of his own. This includes as you have mentioned, to open a consultancy. Therefore, one has to think if he would want to give up this plan. If he really does want to go ahead with it, he would look for ways to evict you out of his property. Therefore, i believe that you should look at the various legal rights that you have for having stayed there for the past 25 years and wanting to continue the possession of the property!
I suggest that you get a reliable advice from a Practicing property lawyer after telling him all the details about your case. One website that you can use is www.lawkonect.com. You can post a detailed query of yours outlining your pesent situation and the same would be answered by Property lawyers with large exerience in rent disputes. You would receve a written response along with information on the relevant laws and the options available to you in your situation. This would help you in taking an informed decision going forward.