Thanks for comments so far. Seeing your comment, Martin, I realise I may have misled readers. The camera was a MF P654N and I used its matrix metering which I have always found to be very accurate. The focus point was the grandkids who were on the lawn and in sunshine. The strange thing is that the bubbles they were blowing have come out very well which wasn't what I would have expected in a less than ideal neg. Most of the shadows beyond the kids and caused by an apple tree were far from solid black. The dog was relatively featureless in shadow terms but it was a coal-black labrador and under the shade of the tree
It is almost as if the print could have done with being grade 6 to get the ideal "snap and sparkle" I was looking for.
It may be that the film required longer development, although normally the manufacturer's times are designed to give a contrast index that ensures reasonable prints on grade 2.5-3, although as I said even the meatier looking negs on the roll needed grade 3.5.
Convention seems to say that a lower ISO and less development time are called for.
You are probably right about the yellow filter in terms of it being unnecessary but the exposure compensation for it at 1/180 was there.
In similar sunshine and on the same lawn( zone V) with the same camera I had tried to test the sunny f11 rule without a filter and the reading over several days in the same time window gave me 1/350 which is close to 1/400.
I am still a bit puzzled
Incidentally but somewhat irrelevant to the main topic I came across the same phenomenon that others have mentioned, namely the need to increase grade when the enlargement is large. My lens was a 75mm and I was further away from the kids than was ideal so the print of the full size neg looked OK or OKish on grade 4 but the print from the more enlarged and cropped projection to make the kids stand out certainly needed grade 5 in my book
Mike