Download the offline installer: Flash Player 188.8.131.52 (Mac OS X)
Save it (right click the link and "Download Linked File as") and quit Safari.
Double click the DMG to "mount it" and a window will open showing the installer - DO NOT run it!
Right click the installer and "Show Package Contents"
Inside Contents/Resources, double click the Adobe Flash Player.pkg
A "COCOA" installer will launch. Follow the instructions to install it.
Open Safari again and click Safari>Preferences
Under the Security tab, check that "Allow Plug-ins" is checked.
Thankyou - worked like a dream!