I used to wonder what it was like for Holmes to look in a mirror and see the face of a stranger looking back. Of course, he would know who it was, but did he, sometimes, give a slight start of surprise, before smiling to himself, knowing that the disguise he had adopted was an excellent one.

For myself, I was not prone to considering myself in the mirror. In the morning, when I shaved, I didn’t really consider my face, other than to ensure that my shave was reasonably accurate. Even then, when I’ve been tired, on occasions Mrs Hudson, on bringing up the breakfast, has enquired whether I would like the mirror cleaning, or, as she grew more used to her erratic lodgers, if I had thought to open my eyes whilst I shaved.

Occasionally, I would glance at myself late at night, when I would frequently look older, tired, and sometimes simply defeated when a patient had not responded to treatment. And I had long since given up on using a mirror to tie a bowtie, preferring to ask Holmes to assist me. He would then maintain I was as handsome as ever, but I would never look at my face to confirm it.

But strangely, now we are retired, I seem to be looking at myself more often. Perhaps it is because I know that if I stay in front of the mirror once I have shaved, Holmes will come past and I will see his smiling face reflected beside mine. Both our faces show signs of aging, but the stress and tiredness have faded and our expressions show contentment as we spend our last years together.