Filling a long column of names

Dear all,

I have one column with 70K of names that vary in their string lenghts.
Each name is the top cell in its group of cells in the same column. The rest of the cells in each group is just an underscore which means "ditto" for the top name of the group.

I'm attaching a simple example for illustration. The top group in that file is:
Whittemore
_
_
_
_
_
_
_
_
_


What is required is to replace the underscore with the top name of the group so it becomes:
Whittemore
Whittemore
Whittemore
Whittemore
Whittemore
Whittemore
Whittemore
Whittemore
Whittemore
Whittemore

More names are set in the attached file.

Can I get some precious help with this question, please?

Many thanks in advance.

T.

honestly .. it has been my privilage that my question attracted all those great minds to solve it. All suggested solutions worked to the desired result, but of course, with different processing time. The fastest was Sintek's first solution, which I implemented on the real data file after trying all those great solutions.

I respectfully ask everyone participated in solving this question to accept my deep gratitude.

Thank you very much.

T.