Do you think that's so? I'd be surprised - the demonetisation of the farthing was trailed for quite some time, was a unique event at the time being years before decimalisation, and being such a near worthless denomination, people could well afford to put aside as many as they wanted. For example, the 1956 was quite a low mintage and listed as a 'key date' in the 60s, but it's not even scarce! There were copious amounts of farthings available for pence in the late 60s, which implies that a massive amount were saved from the melting pot. They weren't rounded up as part of the decimalisation melt either.