The write up on this Mini limo is here: https://www.mini-cooper1.com/mini_limo.html

Was that Kahonwes's?

Don't forget the Mini Limo

Markiss.. in the UK.. you can  get it road legal with IVA..  individual  type approval..I know this because www.mokeinternational.com  just do this on 120 Petrol ( gas) mokes.. for the UK.. in 2021/2022.. Same here with MVR 55  kit car rebuild..  on the gas mokes..in the USA.. PHD

Two doors too many, IMO.
I was going to say to ask about it on the 'Ruined Minis' FB page, but the topic already exists just recently with the same photo. Someone is claiming to have built it himself, another shows a '62-'63 prototype photo, and another entry with a similar build from someone else. 
There's a plate on it, so I'm thinking it may not be the prototype, as most (if not all) prototypes don't have road legal production VINs to register for road use. 

Thanks for the input.
I just Googled "Four door classic Mini" on Microsoft Bing and several of them popped up.
I'll call my buddy who is a Rover historian and works at Gaydon Heritage Motor Center to see if he can throw some light on this.
His father was the R & D director at Rover and my Scout master in the 60's.
I was there last month and there were many R & D Rover & BMC prototypes that never made production (the twin engine Moke for one).

1963SV3  I do NOT make the rules for imports for Minis or land rovers..  CBP has got so strict they even require OEM engines in the LR 110s , 90s. and classic minis.. now  just heads up.. as for Ringo Starr hatchback.. 50/50 shot to import  just depends on what port you import to in the USA.  I think they are 326 ports of entry in the USA..  Baltimore , Charleston SC and Gavleston SC. are super strict . PHD

Probably not DIY.

However, while the “Factory” didn’t market a 4 door Mini there were lots of prototypes so who knows.....and a there was a thriving industry (Woods and Pickets etc) in modded Minis eg hatchbacks, convertibles etc. There was a 4 door Mini (actaually a Clubman I think???) run in one of those trans world rally’s back when.

While Bill categorically states “NO CONVERSIONS”.... I wonder how US Customs might react if someone sought to import, say, Ringo Star’s hatchback....????

BTW Fiat Jollies and the Mini Beach cars were factory builds so not strictly “conversions”.

Cheers, Ian

NO  British Leyland did NOT make four door classic mini.. btw. this type conversions can NOT be imported to the USA.. like the Keiths cabrios or shortys.. but the   conversions with the wicker tops like the Fiat Jollys can be imported to the USA.. I saw one at MME in 2003 in Magog Quebec.. and one fetched $253 large on BaT last year..  cheers PHD.

Did a four door Mini ever exist or was this a DIY conversion?