AND if the solicitor is with it, he or she will a) make a full and detailed attendance note stating the circumstances of execution, conversation, who was present. And I MEAN full and detailed. (Ie, I would pretty much want to know the number of breaths taken!!!, but I'm picky). and b) will ensure that the witnesses are reliable and easily contactable.
Of course this is only really going to be an issue if there is the likelihood of a challenge. But you never know.........