Thanks to your encouragement and my wife's determination (with whom I run) we have just finished our twenty minute run. Daunting to start with but when we got into our rhythm it got a little easier. We begin to believe we will get to the thirty minutes.
My wife is booked to do Race for Life in July and is looking on course for a good run.
To anyone approaching W5R3, if this old fogey can do it, you definitely can!