OK, so here's the report three weeks later, and I'm afraid it's not great news!
Although he looked like this nine days after spraying.....
Stripey lamb is not very stripey any more:
Also the number marked on his side in red is no longer legible.
The orange numbers have done a bit better, and are still clearly readable on all the ewes:
Although some of the lamb marks were hard to read clearly. This was a two I think:
but it's clearly lost a hell of a lot of definition when compared with this photo from less than two weeks ago:
So all in all, I'm unimpressed. Until somebody brings out a spray that really works, we'll be marking with orange numbers at birth, renewing after two weeks, and then putting tags in when they get their first heptavac.
What a pity
.