I'm now going to round up this article series with this last piece of advice:
You don't need to reveal your client's name nor the company he's representing after the testimonials, especially if you agreed to grant him his Right to Confidentiality.
There are a few things regarding business transactions that need to be kept confidential, and freelancing is not exempted from this. Whatever intentions your clients may have for wanting to keep things private, you should respect that as his preference.
I have mentioned in one of my earliest posts that you should provide your clients with the Right to Confidentiality, where you write down in a separate portion of your Freelancer's Contract that you will keep the details of your transactions under discretion.
While you will come across clients who will find it perfectly fine that you cite their names along with the work you've done for them for your portfolio, there will always be a few others who prefer not to have the details of their projects disclosed to a third party.
And the Right to Confidentiality is something that you, a freelancing professional, must not break no matter what the circumstances are. It's easy to prove your competence, much like acquiring and honing your skills. But gaining the trust of your clients and building a solid reputation will be much harder than you think.
So once you have collected a sizable number of testimonials (say, four to six, or even more), simply exclude all of your clients' names. Potential clients will never assume that you merely made up all those glowing testimonials proving your worth as a freelancing professional.