I am a fan of the P&O brand, but the steady flagging out and outsourcing has become very notable.
First it was Pandoro vessels which received Bermuda (Hamilton) status, then when Pandoro and P&O European Ferries (Larne) merged to form P&O Irish Sea, all vessels were moved to either Bermuda or Bahamas register.
Then Pride of Bilbao was moved to Nassau. As this was a charter vessel, not much fuss was made.
Next was P&O's North Sea vessels - Pride of Hull and Pride of York (Norsea) transferring to Bahamas registry. Dutch counterparts (POR and POB) remained registered in Netherlands.
And finally with Brexit, P&O stated their intention of moving Spirit of Britain (Current flagship) and Spirit of France to Cypriot registry. When no adverse press coverage occurred, P&O decided to move all remaining UK flagged vessels to the Cypriot registry.
The result is P&O have not one vessel under the UK flag. It would be sad, but Stena may well use the P&O strategy.
I am also skeptical about Stena's reasons. P&O Ferries choose to flag most of its fleet in the Bahamas (Nassau) - not in the EU! Likewise Norbay has operated for years out of Dublin with Hamilton (Bermuda) as her homeport, with no operational problems.
This could also be the start of agency / outsourced crews (similar to Irish Ferries / Matrix model)being deployed at Stena.
It will be interesting to see the reaction. Not much fuss made when W.B. Yeats arrived with a Cypriot flag, guess Stena were observing and are anticipating little or no negative coverage.
From the pictures I wouldn't consider Stena Estrid outstanding. As for interior comfort and styling, I think W.B. Yeats easily beats Estrid. It looks like Stena went to IKEA and got lots of cheap, hard and nasty seating. That being said she is a very impressive vessel. Certainly her sister will be a big success for Birkenhead / Liverpool operation. First real passenger ferry for the route, rather than a freighter.
Firstly the P&O ships reflagged since the referendum were flagged to Cyprus, not the Bahamas.
Secondly, have you been on the Yeats? The Estrid to me looks rather more comfortable we know for sure had a larger budget for interior design, fixtures and fittings.