It is interesting because the letter says that John Drury was encouraging him to contact his mother, and yet they were living apart at the time, the letter also makes that clear. I wonder if he did ever contact her.
I imagine that the letter must have been very important to Robert to have been kept all this time.
I am pleased to have been able to prove the contents of the letter to be correct, there was no love lost between the writer of the letter and her brothers widow, so my first thought was she was making trouble with her nephew by telling him these things.
So thanks everyone for your help with this!