Further to this matter, confusion has reigned, not helped by my flailing around with alternatives, but I have now gotten some order into the problem.
The Arduino example works in that it will at least consistently initialise the card. The Jeremy Blum sketch does not work in that it consistently fails to initialise the same card.
Neither sketch works with the LCD shield in place. I will put that down to the shield.
On startup with a fresh, clean, card, The Arduino sketch will write "testing 1,2,3." three times. When I press reset, it will write one new line only. So it is only on startup that I have a problem.