The simple answer is that almost all, if not all of them, have a consultancy arm.
The more complex answer is that the consulting they do tends to be dominated by their mainstream activity so a lot of their work isn't what the more snobbish denizens of this place would term proper consulting. Having said that it isn't a lot different from the bulk of the work at E&Y, ACN, Deloittes etc. though with more of an IT element
