Possible Clues:

• Being naughty. they're not up to ten and not, by the sound of them
• How naughty it might have been to get them in the neck having got one over the eight
• Naughty decade
• It's some time since the knots got to be one over th eight
• The number of knots that have just come to an end
• They were naughty
• A number of bonds are for a 10-year period
• Being one over the eight gets one knotted
• The naughty time when Einstein was around
• The last decade