Those are are lovely clear photos. They show the caterpillars more closely and some of them have yellow markings down their sides. This would make them Small Tortoiseshells rather than Peacocks which was my original thought. The actual identity of the species will become clearer after the next moult.
Just one word of warning. If they are Small Tortoiseshells they can have a high mortality rate, but only time will tell.
Please keep us all updated, by adding further posts to this topic.
Last month I collected 7 Peacock and 5 Small Tortoiseshell caterpillars for study purposes. So far I have lost 3 Peacock (to parasites) and all of the Small Tortoiseshell (to disease). All of these were pre-existing conditions and there was nothing I could have done to prevent this happening. In the light of this you may wish to collect 12 caterpillars. If more than 6 survive to pupation you then have the option of releasing the surplus individuals. I do not condone taking large numbers of caterpillars from the wild, but my advice in this instance is tailored to the particular circumstances of this case and based on the assumption that any emerging adult butterflies are released in a suitable location.
i plan to take them back to where we found them to let them go as i'm taken it there the right food and things for them there as i found so meny catpillers . we only live 5 mins away from where they are so not hard to take them back