Herman Miller Aeron
In the movie Casino Royale (2006), when James Bond (Daniel Craig) is in M's apartment, using her laptop, he sits on a Herman Miller Aeron office chair.
The Herman Miller Aeron, designed by Bill Stumpf and Don Chadwick, has become an icon in chair design and is featured in the Museum of Modern Art in New York (MoMa).
The chair is supposed to be very ergonomic although this has been recently been contested. The elements of the chair are highly adjustable though, so it can be made into a very comfortable working chair. There are three sizes of this chair, the small (A), medium (B) and large (C).
The Herman Miller Aeron chair can be configured with many different options. The chair owned by M and used by Bond is one of the top models, with polished aluminum base with graphite frame, grey black tuxedo weave seat and back, adjustable arms, black leather arms pads, and it does seem to have the v-shaped PostureFit lumbar support kit. Unfortunately it is difficult to see which size M's chair is, but when you get one it is advised you get the right size for you.
Prices for the Herman Miller range from $700 - $1170 (or £870 - £1095 in the UK) depending on the configuration. A chair configured like M's chair is available on Amazon for $1170 / £1040. If you're looking to spend less, then try eBay, as plenty of these chairs are available. Often they're only used for conferences or fairs and then sold, so you could get a barely used model for a reduced price.
The Herman Miller Aeron is not only one of the most popular office chairs, it can also be spotted in many other films and television series. In The World Is Not Enough (1999), we can briefly see Elektra King sit on a Herman Miller Areon chair in her 'office' (the construction site shed) in Azerbaijan when she talks to Bond.
In M's apartment, we also see another famous designer chairs, that M and Bond sit on: Knoll Barcelona chairs.