Do you know this for a Fact?..

Not in the sense of being present at the transaction, but in the sense of having read similar accounts in a number of seeming crediable sources. Woodward was simply out of commissions to build guns and was facing bankruptcy. My understanding is that Woodward approached Purdey in 1948 with an offer to sell based on something like Purdey was the only one Woodward would sell to. Purdey seems to have wanted the Woodward O/U. I remember that the price was near 150 GBP.

This could be urban legend with frequent repetition. But, it does seem to fit the circumstances - 1948 was tough times in the UK.