var mess = new Array(
'<img src="http://www.green-space.org.uk/Images/Randomhome/1.jpg">',
'<img src="http://www.green-space.org.uk/Images/Randomhome/2.jpg">',
'<img src="http://www.green-space.org.uk/Images/Randomhome/3.jpg">',
'<img src="http://www.green-space.org.uk/Images/Randomhome/4.jpg">',
'<img src="http://www.green-space.org.uk/Images/Randomhome/5.jpg">',
'<img src="http://www.green-space.org.uk/Images/Randomhome/6.jpg">',
'<img src="http://www.green-space.org.uk/Images/Randomhome/7.jpg">',
'<img src="http://www.green-space.org.uk/Images/Randomhome/8.jpg">');
var max = mess.length;
var num = Math.floor((Math.random() * max));
document.writeln(mess[num]);