Edward I reigned from 1272 to 1307, and Robert the Bruce was King of Scotland from 1306 to 1329. Adfam Smith wrote 'The Wealth of Nations' in the 1770's, so we are talking about devaluation over a period of about 470 years.
To maintain purchasing parity for a currency devalued to 1/3 of its original value over 470 years, like the pound sterling, would require compound interest at a rate of about 0.24%.
In the case of the Scottish pound, reduced to 1/36thof its value over that period, a compound interest rate of 0.77% is necessary just to break even.
This puts Gordon Brown's inflation target of two to three percent, widely described as low, in a historical context. This target rate has been exceeded on several occasions, but of course, inflation hasn't come in below the target range.
2 to 3 per cent is a historically low inflation rate only if you think that history began in the 1970's.
2 per cent over 470 years would leave the poor GBP (Gordon Broon Poond) at 1/11,000 th of it's original value. 3 percent to less than 1 millionth of it's original worth. At the moment the inflation rate is expected top reach 4 per cent, which would lead to the pound being less than 1 / 100 millionth of its value over 470 years.
So the klepto chancellor's legendary proodence had led to a situation when the pound is devaluing at a rate which would be 33 million times worse than the combined efforts of some notably greedy tyrants and spendthrift wastrals over the centuries.