I have phoned earlier Terry.....They have helped me before a couple of years ago ,although he wanted to confirm with someone else who wasnt available and to see if anything is recorded.
.One of the reasons i have been given previously is due to there not being any going into circulation the year before ,they did not want pennies to be hoarded or given at Christmas to kids which apparently was common then.If that was one of the reasons it definately worked as 1934 pennies in Mint state are extremely hard to find as you know.
All the other bronze wasnt treated ,maybe kids would of been negged out with a farthing for christmas so didnt think it was worth it