I can't help with how she crossed the Atlantic, but it prompted me to try to find which ship she went to France on. Reading her dispatch on:

[www.theguardian.com]

it seems that she went on one of the hospital carriers marked with a * in the list below; can anyone pin down which one?

Hospital Carriers

* DINARD
* LADY CONNAUGHT
* NAUSHON
* PRAGUE
* ST JULIEN (mined)

* British merchant crew, with US medics - for US beaches