The facts are simple enough. The client decided that it wanted certain things done. The consultant responded to the need as defined by the client. Unfortunately, the client's real need proved to be quite different. The client felt that it had wasted its money and was unhappy with the consultant. The assignment ended in acrimony.
I suppose that I have now completed on my own or managed something over 300 consulting assignments. Inevitably a proportion, perhaps as much as 5 per cent, have gone wrong in some way. When I look at the reasons for this, the most common cause is failure at the diagnostic stage.
I have no magic bullet here. However, there are a couple of things that you can do to minimise the risks.
In scoping jobs, we all talk about what the client wants done. Less often, we talk about why the client wants the job done. Yet this is critical, especially in consulting assignments. If you do not understand how the client intends to use your advice or analysis, then your chances of picking up mistakes in the way scope is defined will be much reduced.
The second thing that you can do is to seek to suss out internal stakeholders and decision points.
One of my worst ever failures on a job - in this case for a Government agency - occurred because I did not identify a key decision maker whose views on the job were different from my immediate client.
It was a strategy assignment. I defined a process to create that strategy. There was also a research or industry analysis component. I focused on this as an input to the strategy process. It turned out that the decision maker in question regarded this as the key component. To his mind, the development of the strategy itself was really a matter for the agency.
This difference in approach did not become clear until half way through the assignment. Then, suddenly, we had to change direction. The results satisfied no-one.
The third thing is to document and clear as you go along. This increases your chances of discovering mis-definition of scope early. It also protects your legal position.
None of this is rocket science. But it may help.