Well done, that did the trick!
I had already changed 203 to 60 but never twigged that it was picking up character sizes as well. In any event your solution is better because I see now that Bigpond IP addresses sometimes start with 203.
The script works fine now, although it still picks up some of the HTML code

[TiVo [p0] /tmp]# cat /tmp/ip.txt
<html><head><title>Current IP Check</title></head><body>Current IP Address: 203. 51.17.173</body></html>

Is this what you would expect?