Nick Bailey is an agent with the British Secret Service.
We do not know very much about this man except that he has been, by the way he is treated with respect and the way he deals with his immediate superior, an operative for quite some time and obviously has a considerable about of experience handling very tricky missions. The ease with which his boss hands to him a couple of dangerous but important assignments and the nonchalant way he accepts them and heads off with worry speak volumes.
Bailey is, by the looks of him, in his late 30's or early 40's. He sports moderate-length black hair presented in a conservative style. He is always seen wearing a suit and tie, even out in the field, and those items are as plain vanilla as can be showing the man does not go for flashy at all. He is still quite memorable, however, due to the black patch he wears over his left eye [I have no idea yet how he came to need the item].
It is said of Bailey as well as his colleagues, "The British Secret Service agent is a man of highly-trained ability. At all times he must be on the alert - to spot not only the unusual but the simple, everyday things of life, as well, for it can sometimes happen that in what appears to be a task of monotonous normality ... there lurks a pervading shadow of evil." That 'shadow of evil' extends to the things that Bailey has to do in his job. He is required to kill enemy soldiers up close with a knife and with no hesitation knowing that his own death would be certain if he made a mistake.
Bailey may or may not hold the rank of Colonel in the British Army. He shows credentials pointing to that fact in at least one adventure and he certainly carries himself like a man expecting to be obeyed but being a good undercover operative, it may just be one of his many covers.