Help with merge duplicates rows and concatenate non matching data

Hi All,

New to forum, looking for some help with a macro that would look up duplicate cells in column A, merge the rows based on that cell and concatenate any data in the cells that did not match.

Kinda difficult to explain, need it for a mail merge to stop sending multiple letters to the same client. For example, the grid looks a bit like this:

0001| Mr Joe Blogs | Henry | Dog|
0002| Mr David Cameron| Cleg| Dog|
0003| Mr John Stewart| Charlie| Dog|
0001| Mr Joe Blogs| Alice| Horse|
0002| Mr David Cameron| Gove| Dog|
0003| Mrs Allison Stewart| Ella| Cat|
0004| Mr Paul Stewart| Pancho| Dog|

With a macro producing:

0001| Mr Joe Blogs| Henry, Alice| Dog, Horse|
0002| Mr David Cameron| Cleg, Gove| Dog|
0003| Mr John Stewart, Mrs Allison Stewart| Charlie, Ella| Dog, Cat|
0004| Mr Paul Stewart| Pancho| Dog|

The spread sheet will have many columns and 1000s of rows.

Many Thanks,
John