My point was that if Bitcoin attempted to make anything like a similar promise, it would be ridiculed at best, and litigated against at worst.
Just because it is a historical promise does not allow one to make it without being quite clear what it purports to promising.
If I were to produce a financial contract with similar wording, the FSA would rush to my house to complain.
2 points to make
1. ever since the minimum wage came in. it became widely known that one hours minimum wage is worth £6.20 .. and a mirror to that obviously is that £6.20 is worth 1 hours minimum wage. put it into context of other things. EG a loaf of bread or 4 pints of milk are worth 10 minutes of minimal labour each.
now on that scale the promise would be that you will be paid in something in the equivalent to just over 1 hour 30 minutes of minimal labour in exchange for a £10 note if the bank note disapeared and the government had to trade your bank notes for something new/different.
now lets move onto bitcoin. although its harder to judge true value. i have seen the network hash rate of mining and seen similar waves as the network hashrate sky rocks so has the price. and where the price sky rockets totally unrelated to network hash rate thats where things like the 2011 spike and dump happens.
as long as you can see some form of correlation between new users buying into bitcoin, network hashrate. then bitcoin has a value. if you cannot see the price follow any pattern or statistic at all, then its a speculated bubble.
bitcoin is still too new to have one single set guideline for its value.
point 2.
FSA have no issues of you making bearer bonds and promisary notes. they do however have issues with reproducing the UK pound note using the word 'pound' the symbol '£' and the queens face all in one place without their consent or explanation. but so as long as you ask FSA and the UK government you can (with alot of paperwork and red tape) make your own pound note.
take these guys for instance.
http://bristolpound.org/