Posted: 13/07/2015 at 14:00
It certainly is a party wall jo47. (see diagram 4)
"Some works on a party wall may be so minor that service of notice under the Act would be generally regarded as not necessary.
• drilling into a party wall to fix plugs and screws for ordinary wall units or shelving
• cutting into a party wall to add or replace recessed electric wiring and sockets
• removing old plaster and replastering
may all be too minor to require a notice under the Act.
However, the key point is whether your planned work might have any possible consequences for the structural strength and support functions of the party wall as a whole, or cause damage to the Adjoining Owner's side of the wall. If you are in doubt about whether your planned work requires a notice you might wish to seek advice from a qualified building professional."