The debate continues.
On 10/1/2012, Edward Vandyk wrote:
"I am restoring a 1600-Mk-II 'Deluxe' coupe and want sun visors. The SPL AKD5014 (a 1500 parts list) gives a part number of AHH5710 and illustrates a sun visor with a 'rectangular' hinge similar to the one you say is wrong for the MGA and correct for the A30. The SPL AKD1296 (a Twin cam parts list) gives the same part number and says it is no longer available but replaced by part number AHE5000. The change point being at Twin Cam 2061. The illustration in the SPL is again rectangular not triangular. The 1600 part list (which illustrates the rectangular hinge) shows a change over at car 81532 which is December 1959 but your CF125 records the earlier Twin Cam changeover on 5 May 1959 for the Twin Cam when this home market (YM1) coupe was specified as having factory fitted sun visors.

Service Parts List for MGA 1500, 1600, and Twin Cam all have similar illustration, and all list the same part number for the sun visor, AHH5710. The 1600 SPL (latest of the publications) has an additional note, "not available use AHE5000". This is not a change of production part number, but implies a different part number (and possibly different configuration of the part) is available for replacement parts (back in the day).

"Original MGA" lists a production change of the sun visor at Twin Cam (c)2061 (May 1959) and for the standard Coupe at (c)81532 (Dec 1959). This later change came coincidentally very near the end of Twin Cam production.

At 08:47 PM 10/3/2012, Bo Giersing wrote: "The photo of the sun visor is attached. [See below]. I can confirm with certainty that the holes in the bracket fits the mounting holes in 554 [Twin Cam coupe] exactly – 554 was fitted from the factory with one sun visor, and it did not have a triangular bracket with 3 screws. The sun visor also looks much the same as the illustration in both the 1600 and Twin Cam SPL". At 09:21 PM 10/3/2012, Bo Giersing wrote: "I have had a quick look at Barneys website, and realized that the triangular hinge refers to the sun visor part, not the mounting holes. My sun visor is exactly the same as one of Barneys illustrations, and in view of the illustration in the SPL, I would think that this is correct – although there may also be other later types".

Rodney Green wrote:
"Is this considered correct. On my VDP hard top".

This is interesting. It makes sense, but is the first time I have heard of a sun visor being attached to a removable hardtop on a roadster.

On 4 Oct 2012, Edward Vandyk wrote:
"Sun Visor info as follows:
1. Only one visor is fitted to the drivers side;
2. Length is 36cm or 14in;
3. Height is 12cm or 4 3/4in;
4. Fixing bracket to the Visor is one captive bolt and nut;
5. Fixing bracket to the roof it 2 screws;
6. Bracket is a two piece rectangle (with which the captive bolt and nut vice around a small metal bar that runs the length of the visor - top side) and is located in the middle of the visor - there is a name Tudor on the underside of the bracket".

The sun visor was an optional accessory. Many cars were delivered with no visors. Some cars had one visor on the drivers side only. Apparently far fewer cars had two visors from the factory records. Any kind of visor could have been field installed as an aftermarket part. There were two part numbers for the factory sun visor on the MGA, AHH5710 and AHE5000. Still hoping to define exactly what those two parts looked like, which look is which part number, and how they are different.

Addendum 31 Jan 2013:
Edward Vandyk wrote:
I went to see YM1 1560 today. You may recall YM1 1560 was fitted with one (not two) factory specified sun visors. Richard tells me the car is as original, including the visor hinge, although he had the sun visor itself recovered. Richard was kind enough to take the visor off to show me the 'Tudor' stamped on the back.

See the Accessories section for information on
aftermasrket sun visors for the Coupe