Originally Posted by
P!N20
On a Claud Butler it's a tyre pump
Handy to have on the velodrome.
I missed the apparent serious sarcasm of the second point. In fact, this is the road/path model with reinforced track dropouts with fender eyelets and brake holes drilled front and rear. It would have been ideal for short time trials such as those that were popular in England at the time (25-mile routes being most likely given the way the bicycle rides, in my opinion). I've seen some of the track-focused frame builds that did not include the pump mounts. So, I think that all makes sense from a functional perspective!
-Gregory