Full Idea
Let us remember that the title in question is not the title to the sobriquet 'Theseus' Ship'; it is the title to identity with Theseus' ship, a particular ship originating from the eighth century B.C.
Clarification
A 'sobriquet' is a label (!)
Gist of Idea
The question is not what gets the title 'Theseus' Ship', but what is identical with the original
Source
David Wiggins (Sameness and Substance Renewed [2001], 3.4)
Book Reference
Wiggins,David: 'Sameness and Substance Renewed' [CUP 2001], p.98
A Reaction
There is an assumption here that identity is defined by origin. What is the origin of the identity of those huge football clubs that began under the name of some village team in 1875? What is the origin of 'England' as a single entity?