The phone cable was actually a quick fix for a faulty gear linkage on the side of the A2 if you remember correctly Shaun. Get it right!
By all accounts, this would be very easy to fit if you have the correct part from Reno. However, I only changed my cable and not the sheaf and the rest of the little bits. I used a £3.99 throttle cable from a Mini City/Mayfair, cut it to length and added a small stopper to one end that fitted perfectly in the actuator under the bonnet. With a bit of added grease, it cost me less than a fiver and only 50 mins to do including the trip to a local family run motor factor. I got quoted about £45 for the part and a 2 week waiting time from Reno.