Be very aware of this company's intentions! The job spec sent out was brief but something one could do. Their format is before you have any Face to Face interview you have to do a coding challenge upon which they will judge you on Design Principles, Approach etc. No time limit is set but they ask for how long it took you to do the test. At first sight the test looks good and relevant to the job you would be doing. When you look into it in a bit more detail though you can see to do the challenge properly it will take several hours (unless of course by some fluke you have done the role before and have a nice architected solution ready to go). Having had a couple of other agencies contact me about this role and asking about candidates who have done this challenge it transpired that at least in the candidates they had everyone has been rejected (approach not good enough). My take on them is this: They are looking for solution approaches to challenges you will meet on the job. That's fine but when you hear no one is being offered the role then this smacks of an approach which is basically using interviewees as a brain repository of getting some good tips and pointers for their own work. I think to do the technical test correctly then an investment of at least 20 hours of time is required (unless of course you have done this all before). You have to ask the question is your time spent better elsewhere. Being a little sceptical, I would say if someone did get to the 2nd stage it would be a Face to Face to pick their brains further.