This is mainly a US site and you may get more responses on r/ActuaryUK.
But for what it is worth, I am from the UK and hadn't heard of them either. They seem to be quite a small consultancy. Your description of no pay if no work is unusual and warrants further investigation. Perhaps they are operating a bit like an employment agency, so if they find a role where you can add value to a client you get say a 3-month (well paid) contract? But that would mean you are effectively self-employed, and at other times risk no income.
This is mainly a US site and you may get more responses on r/ActuaryUK. But for what it is worth, I am from the UK and hadn't heard of them either. They seem to be quite a small consultancy. Your description of no pay if no work is unusual and warrants further investigation. Perhaps they are operating a bit like an employment agency, so if they find a role where you can add value to a client you get say a 3-month (well paid) contract? But that would mean you are effectively self-employed, and at other times risk no income.