£50 000 in £50 notes weighs about 1.3kg. So £50 bn = 1,300 tonnes, or 1,279.46 British long tons, of paper.
In 1936, the Aga Khan was presented with his weight in gold, then 220 lb, or c. 100 kg. Gold currently sells for £14,891.58 per kilo, making the Aga Khan's weight in gold worth £1.49 million in today's prices. However, 100 kg of £50 notes is worth £3.85 million. The £50 notes would weigh as much as 13,027 Aga Khans, but would be worth 33,576"gold-priced Aga Khans".
Or, in pre-crash property terms: it is reported that Sheikh Hamad paid £100 million last year for a penthouse overlooking Hyde Park. Mervyn King has just pledged 500 "Hamads" (or over 700 "Updown Courts", if you prefer).
Or, in height terms:
1 ream of paper (500 sheets) is 5.4 cm thick. So 1 billion £50 notes would make a pile 108 kilometres, or 67.1 miles, high.
Were the Aga Khan of that time to have been the height of the average British man of today (5 ft 9 in, or 1.753 metres), £50 billion would equate to a stack of "gold-priced Aga Khans" (without shoes) almost 59 kilometres high. *
The lowest layer of the Earth's atmosphere, the troposphere, varies from 8km at the poles to 16km over the equator; the ionosphere starts at an altitude of about 80 km, and the US Air Force considers "space" to begin at 81 km.
Perhaps it would be simpler to use a new unit: the "government fudge", one box of which costs £50 billion.
By the way: hands up all those who believe the Prescott bulimia story, of which up to now there was not one breath? Now, hands up all those who have an explanation as to why this story should appear this weekend?
* I think this shows that the Aga Khan was worth twice his height in £50 notes.