We've touched on this topic off and on throughout various watch posts, so I thought it would be useful to have a general discussion of it here.
The issue regards what is, or is not, a valid Bulova signature on a watch case.
There are those who believe that any watch without a Bulova signature inside the case back is not valid, call it a "recase" or a Frankbully, or whatever you like.
However, many of us have watches in our collection that have different signature configurations. I think it would be helpful to all of us to talk about those here and see if we can come to some agreement about their validity.
A good example to start with is the 1934/1935 Ambassador. I have one, and so does Plains, and there may be others in the database as well, that do not have the Bulova signature inside the case. Instead, they have the Bulova signature on the back, along with a symbol that looks somewhat like a shield. There is no other signature on the case anywhere, which is important to note: we are not talking here about cases that bear any other maker's signature.
I just ran across a third example of this same Ambassador model on eBay, and the seller confirmed that it has "Bulova" on the back edge of the case, above the gold content statement, but nothing inside the case back. So, that's THREE EXAMPLES of just one model that have that signature configuration. Seems a bit much for the recase theory, IMO.
I have also seen cases that have only "B -" or "Bulova" on the back, without the shield-like symbol beside it, and nothing at all on the inside.
I believe that many of us have examples of this type of signature in our collection. It would be useful, I believe, to inventory our various collections and see if we can spot trends--such as a date range--that may help us find an answer to this question and put this issue to rest.
It has been suggested that the alternate signature described above is only seen in models from the early-to-mid '30s. It would be interesting to see if we can confirm or refute that proposition, as it would certainly narrow our search for an explanation.
It has also been suggested that the shield-like symbol could be Keystone's logo, suggesting that Keystone made the case--for reasons unknown. However, note that American Standard also used a shield symbol, and we are all well aware of American Standard's connection to Bulova.
I'll take a look at my collection and report back.