After a couple of days, I was getting to the end of the yarn I had here. There two choices - finish where I was or go and buy another ball. After testing it out for length, Daniel said I could finish at the end of the ball. The scarf has ended up just under the ten feet, so not far off the original request.
As you can see, he really got into the spirit of things when I wanted photos. He has since used the scarf and I had a telephone call to say it was brilliant. If he's happy, then I'm happy and he'll be even happier when he gets home. His cardigan is finally finished!