I feel this is the wrong forum for it...but are there any legal eagles here?

Long story short, dad died in December, his will is 15 years old and well out of date at that in regards to executors, i.e not me when it should be.

I'm not sure if the final page is likely to throw up legal issues in regards to its validity though. Can't seem to post the image in landscape for some reason-



Only my gran signed this as a witness. Obviously there is another space for a second witness and the paragraph wording implies more than one witness to me. Anyone have an idea how much of an issue that could be for the will to be considered 'valid'?