BSA Double Diamond/ Piled Arms Tandem Frame?

[Illaveago]

I was asked by my brother If I wanted an old tandem as he knew of one which was going to be to be possibly dumped or disposed of. My answer was. " Yes ! How much?"
My wife and I had fancied the idea of a tandem a while back but had missed out on one at a local auction as we were outbid. So it seemed like a golden opportunity to get one. I contacted my brother's friend to find out the details of the bike. He had had the bike since the 80's and had had it modified a bit, some brackets removed and some fitted before having it repainted. "How much ? " A Tenner!
We arranged a meeting so that I could see it. Meanwhile my imagination started working overtime. I was getting the sparkly images that you see in films. I tried to play down those images and started imagining the total opposite of a rusty old neglected bike. Always best to look on the bright side.
Well the gloomy wet day arrived for me to go and see it / buy it. It was a long journey despite not being far away. A very long story to explain.
The frame was said to be from the 40's and it once had Reynolds 531 on the frame. The wheels had gone 15 years ago. He didn't know the make but said that there was a frame number stamped on it somewhere.
I looked around in his garage and noticed a shiny red tandem

frame suspended by a rope on a wall. It wasn't a beaten up tatty thing that I was looking at. The words " Yes, how much ?" Couldn't come out fast enough. We both lifted the frame down off the wall. I paid £20 as he had an old saddle and stem/ bars as well.
I returned later with my car to collect it. And so my research started.

 

[biggs682]

I can confirm that looks like e nice red tandem so at least it will be quick

 

[Kempstonian]

Lovely! Looks to be in great condition. I notice it has track ends on it, is this usual for tandems? (I don't know much about them)

 

[midlife]

Looks classy, clip type headset so *way* before my time lol

 

[Illaveago]

I did some looking on the net and found a picture of a 1937 BSA Double Diamond with sidecar which was very similar to mine. On closer examination I could see that the lugs looked the same , the shoulders of the front forks although mine do not have the chrome caps looked the same also. The way in which the lamp bracket was fitted to the front fork also matched.
I was a bit puzzled by the rear fork ends but found a drawing in a BSA Winged Wheel manual which showed the same type of rear dropouts. Closer inspection of the picture of the BSA with the sidcar showing the rear wheel fixing revealed a similar dropout. It was hard to see at first but a gap in the back of the dropout could just be seen.
In the images of BSA catalogues the various models are given numbers starting with T for tandem followed by a number denoting the year with a second number denoting whether it had gears or not. I was wondering if my frame number also followed this sequence? I discovered from the previous owner that the tandem originally had gears, so the second 2 could apply.
As for how old the frame is I was told that it was from the 40's. This is where the frame numbering system breaks down, unless he was mistaken and the frame was from the 30' or 50's as I discovered from another web site that cycles were not made during the war period.
Most of my research came from " The Online Bicycle Museum" and "The BSA & Military Bicycle Museum".

 

[midlife]

I think the braze-on on the non drive side chain stay is for a sturmey coaster brake, they go back to the 30's..

 

[Illaveago]

Today I found an article about ", Identifying a BSA" in a June/ July 2010 Veteran - Cycle Club magazine which I found interesting. One part I found said that the seat stays were brazed onto a new patetented design of lug from 1929. It also said that Sports frames had forged rear dropouts with the frame number stamped into the left rear dropout. The article goes on to say that by 1939 it seems that all models were fitted with a headbadge.
I am wondering if my tandem might be a sports model from the 1930's.