This post is for anyone who is searching for the hash # key on a British apple keyboard.
Hold down the “alt/option” key then press “3”
On a U.S. Keyboard it will most likely be “Shift + 3”
If you don’t get a hash appear when you press alt > 3; open the Keyboard Viewer (you will find this on the top right of your screen next to the date and time. It is usually the country flag icon.) Or
Open system preferences > Keyboard > Select ‘Input Sources’ make sure British is selected. You will see the different keyboard characters change when you press alt, shift etc.
For anyone who is an avid Twitter user the # hash key is an important character. As a photographer I post many images via twitter and instagram using the hashtag.