Can anyone help me ID this caterpillar?

[Cw112]

I found this randomly in the house the other day, presumably it came in on a ladder that had been outside for ages. DS made a little habitat for it and it's really enjoying the nasturtium leaves I've put in but not really touched much else? Is it safe to handle? It seems like it's doubled in size in a day!

DS and DIL hate them too. I find this incomprehensible

I had a sycamore moth fall out of a tree on me last year. Lovely creatures. Your caterpillar is a beauty too OP.

The best thing about the hawk moth caterpillars is their poo - presumably they have anuses shaped like an icing nozzle (picture isn't a hawkmoth, but they have the same poo)

This is the beauty of Mumsnet, never before have I thought about the pooing habits of caterpillars and now I know a new word.

I was genuinely delighted to learn that their poop is called frass. Don't ask me why but I think it sounds a bit whimsical. I was not prepared for how much of it there would be and that I need to clean this little dudes habitat out twice a day!

When you consider how much leaf caterpillars can chomp their way through, the volume of output is perhaps unsurprising!

Just a little update on my fluffy friend. He's now massive and ravenous. However the only leaves I've found so far that he seems to like are nasturtium leaves. Unfortunately my nasturtiums aren't doing super well so I'm worried about running out of leaves. Any idea what else I could try feeding it? If anyone would have such wisdom!

Nettle, honeysuckle, hop, birch according to this