It would appear that I have at last had success with lavender cuttings after many failures. I took these latest cuttings last year.
When tearing off the cutting from the plant, the heel can sometimes have a longish tail of bark attached. This won't produce roots and could encourage rotting. It is this outer layer which should be cut off cleanly. Inside there is the lighter core which contains the cells which can become roots. Try to avoid damage to this area by squashing or bruising. There is a higher concentration of root producing cells at junctions between stems, and in the outer layer of the 'inner' stem, which is why we tend to expose this area when attempting cuttings (or grafts).
I used a very light compost with added grit to open it up. I only wanted to take a few cutting from a new plant so put them in individual pots. I used the clear plastic 'cups' you gets with ice cream cones as mini propagators. These make it easy to check the cuttings and dry the inside if by chance it looks too wet. I carefully tipped one out after a few weeks as they appeared to be putting on top growth but there was hardly any root development so repotted it and have left them all for a few months more. I have kept them in an unheated greenhouse throughout and have been careful to keep them on the dry side. I now have very tiny, mini lavender bushes definately putting on top growth, but will keep them in a controlled environment until I can rely on the weather and they are not shocked. Had I rooted them all in the same pot I would have grown them on individually before planting out.
With regard to Standards, these may well be grafted onto the stems of entirely different plants - though I haven't check them out.
Cherrypip: It is my understanding that cuttings of licensed varieties, taken for your own use are ok. Just don't sell them. Someone please correct me if I am wrong.
I hope my experience helps with all of the above queries. My neighbour tells me she takes lavender cuttings easily, but must say, although I have had success with lots of different plants, Lavender has always been a problem.