@Graynomad, this was sloppy copying and pasting on my part - I was halfway through mixing code around when I posted this. The N in the Picaxe program should have been a T. The line
serin 4, T2400, ("initialise"), b1
reads the incoming data into the variable b1, but first must receive the qualifier "initialise". Again, sloppy copying as I omitted
Serial.write("initialise");
from the Arduino code accidently.
~Hope this helps