What's your secret JayG?, my leek seedlings are like yours when they are planted out but only reach the 'biro' stage by now!!
Well done on the Parsnips!
As a leek newbie I can't claim to have discovered any secrets about growing them!
I planted them out in the traditional 6" dibbed holes and watered them in at the beginning of June. I then waved a finger at them and issued the traditional "that's it, it's up to you now. You've got two choices!" warning and left them to it!
A couple of feeds of dried chicken poo, careful weeding making sure I didn't scatter any soil between the leaves, and the occasional watering was the only additional care they got.
(Oh, I did plant some of them "a la Monty Don"; 3 or 4 per planting hole - they're OK but not as big as the single ones needless to say. Whether the yield per planting hole is better or worse I can't really say at the moment.)
As for the parsnips, they have performed much better since my discovery a few years ago that sandy soil can be nutrient-deficient for veg and although parsnips will fork in newly-manured ground that doesn't mean they will flourish if half starved to death!