Dear Mr. Allan Martin,
Please allow me to make an introduction to you. The bearer of this letter is the person that I was talking to you about who is an expert on the problem that you are currently having.
As I have said earlier, I have several persons in my office that can help you with it. I have chosen him because of his knowledge on the field and also of his familiarity with the area. This will take do away with burdening you with meeting him and offering him some accommodations. He has friends and family who are still in town and he will just go there if he needs a place to sleep in.
If you will be so kind as to provide him with a member of your staff for a tour of the facilities, it will be greatly appreciated. Thank you.