Thanks to everyone for your replies. I have sown more seeds today from different supplier, so will see what these are like. I have never saved peas to use as seeds, only runner beans, if this next lot are successful I will save some and hope for a better crop!! I did email Unwins and received the reply....
"The reasons the pods are not as they usually are is due to the low light level we have had this year. Most things are not growing as they would normally be if we were having a proper summer". This "low light level" is not affecting any of my other crops, in fact everything else is producing more successful and heavier yields than usual despite the lack of sun and a higher rainfall. I suppose it depends where you live but has anyone else had a better year because of the rain?