Thank you all for your input on this. I am aware of the problems caused by not being absolutely precise in making sure lines do meet at a point and not just sort of at a point. Hours spent finding where the offending point was.
This raises another query but I will start another thread as it is not related to this.
Sorry it's taken so long to thank you, John, for your input. I have not followed our proposals - yet - but I have noted what you have said and will in future if I need to input a jpg file.