>>...if only to fit in with the Olympic and Titanic?<<
I have the impression from this that you mean a ship other then either the Olympic and Titanic. If this is the case, exactly what ship would you be referring to?
If it's the Britannic, to my knowladge, the clock was never fitted as the ship was at least partly stripped of some of her fittings for wartime service. That it was fitted on the Olympic is a documented fact courtesy of a well known photo of the Olympic's Grand Staircase.
If it's the Titanic you're referring to, there has been some controversy over that. Some aspects of the Titanic's fitting out were a bit rushed in order to get the ship into service after several delays. As a possible consequence of this, the clock may have been left on the beach as fitting it in was not a priority. Since no photos of the Titanic's intact Grand Staircase are known to have survived to the present day, this can't be verified one way or another.