SOLVED: Problem compiling code error: "undefined Reference to 'Timer1'"

From reading the error, it seems every reference you make to Timer1 is undefined.
I am wondering if you have verified the location of your TimeOne library?
Also, just a small thought is going through my mind say that Arduino libraries are included with a slight syntax difference to external libraries;
I use quotes to include files, not generally between <> brackets.
Can someone confirm this?

Is your library imported into the Arduino library or have you kept it external?

#include "Arduino.h"
#include "PinChangeInt.h"
#include "TimerOne.h"

Paul