For some reason now every post is in reverse order so I have to go to last page to read the first post and work backwards.

Bit annoying. Wondering if I have pressed a button somewhere without realizing it or is anyone else experiencing this.

This is an option in your Profile.  To change it:

Click the "User CP" tab.
Click on the "Profile" tab below that.
Click the "Options" link on the left (it will ask for your password).
Scroll down towards the bottom.  You will see a checkbox next to "Do you want to reverse the displayed order of posts in the topic?".
Uncheck that and click the "Save Changes" button.

Thank you. Strange how that button got flicked on. Never been into the options menu before