The 5" Butch loco was originally designed by Dick Simmonds of Erith in Kent as one of a series of four very similar locos 0-4-0 & 0-6-0 in both 5" and 7¼" gauges, however I don't think there was ever a serial published.
The Dick Simmonds business was bought by Reeves.
If you search the ME index there are numerous references to Butch which might repay looking up if you (or your local library) has access to the copies. Several of these references refer to a Butch as a club loco at the Rugby club, but this was a long time ago.