Can anyone tell me if there is a difference between an undergraduate's starting salary and a pre-work experience masters' starting salary in the big 4 consulting firms? And what are they likely to be in London at the moment?

Nil difference.

I second that. Outside the green dot the other big 4 firms have a very small (if any) intake for consulting roles at grad level

what's a green dot?

Green dot = Deloitte Consulting

I joined Mckinsey with a masters at JA level, and got 35% more than analysts with an undergrad.

O Rly

it all depends on what line of work u are in. For instance, in the clinical healthcare or research field, masters goes a very long way. Same for specialised consulting such as in depth engineering consulting.For most broad based big 4 type IT/Business consulting, there isnt much difference in salary. the masters will give u a bit of an advantage over other applicants- but work experience counts for the most here. Salary wise, i'd say about a measly 5% increment over bachelors...really not much and may leave you wondering if its worth it.That 5% is from job to job over your career, so in the long run it is worth it.

In almost all cases, the answer is zero.I would strongly query the reasons for doing a Masters unless it was for a deeply technical subject. Why would you want to defer going into the workplace and earning a living, rather than spending another year cogitating over theoretical discourse

Uni is fun.