Sherlock Holmes

He also can't really be seen swanning around downstairs as the most wanted man in London.

So, what does he do?

He enters the underground parking structure, nicks a lift keycard from one of his old cars still parked there, into the lift he goes, climbs out through this panel on his old floor.

Oh, it's not impossible.

Certainly not for a man of six foot seven.

Not too difficult for me either.

John would struggle.

And me.

Yes, but I can explain.

Go back to Gregson and back to the mirror.

Oh, what the bloody hell is going on?

How ingenious.

Are you in the mirror?

Our killer sat in this cubby off the lift walls.

scraped a line of sight through the insulation and plaster and, having been the former resident, knew exactly where to place his bespoke miniature rifle and where to fire his bespoke and miniature bullet.

Just as our victim was gazing at his own reflection, a bullet shot through and punctured him right in the neck.

Why the neck?

So he could enter.

Exactly.

Enter, finish off our victim, and rig it to explode upon our investigation.