And let's for fun sake extrapolate the cost 

2/-6 was 12.5 pence in 1971 

Therefore 9.90 is the same fraction that 2,/-6 was for 240 pence in the pound 

Using this would make an old pound worth £190.08 of today's money. 
#money #inflation #devaluingthepound  #bankofengland
#money #inflation #devaluingthepound #bankofengland