An update on this:
On arriving home I removed the whole blind assembly and brought inside to a large work table to have a more detailed examination of the problem.
There are two cords on either side which cross over in the middle of the blind and then fixed in place with a small metal crimp at each end at the bottom. The cords on the bottom left had detached themselves from the crimped stopper and were hanging loose. Clearly I think they had been over tensioned when fitted and eventually worked free.
I was left with the dilemma that the offending cords had been trimmed too short on that side to secure in place at a lesser tension. I had after much trawling of these forums found a post which described a similar problem which had been solved with the use of thin cable ties at each end which could be attached to The retaining bracket at the bo of each end, looped around and attached to the cord, then adjusting to an optimal tension.
So that’s what I tried, and hey presto! Turned into a perfect job!
Needless to say after reading many tales of costly replacement blinds for this problem, the cost of my fix was literally pennies.
The bind has been back up for a few day now with all new fixings intact.
Result!
Happy to assist anyone who may have suffered a similar problem
Thanks
Jim