Disaster.  It seems that all your precautions have failed and your darling brother/sister/son/daughter has been exchanged for a changeling.  But how to be sure that the puling, wizened creature in the cradle really is a fairy usurper?

Here are some sure-fire 17th century changeling detection methods to set your mind at rest.

1.  Place hops and malt in an eggshell and heat over the fire.  The changeling will be so surprised by this strange practice it will unmask itself by exclaiming something along the lines of: ‘I have seen three forests grow and wither, but I never saw ale brewed in an eggshell before.’

2.  Leave bagpipes lying around the house.  The urge to play them will be too strong for the fairy to resist.

3.  Leave two suspected changelings babies in a room together: when they think the coast is clear they will engage in precocious conversation.

If any of these methods confirm your worst fears, then watch this space: my next post will tell you how to get your original darling child back.