I bought some garden bulbs at the ideal home exhibition and was told to stand them in the window and not to water them until a flower appeared. I have done that and a leaf has now appeared but is giving a smell just like sewage. I cannot remember what the bulb was called so I cannot trace it to see if this is normal. Please does anybody know this bulb?

No idea. I suspect that the bulb is rotting, not a particular plant that smells like sewage.
Did you water when the sprout appeared?