Is it necessary to have a show lead in a breed ring? If it is do I have to remove the collar or leave it on incase of anything that may happen? 

Most breeds are shown on a thin sliplead or half-check collar and lead, because you don't want a bulky collar disguising the shape of the neck and shoulders. The regular collar is taken off before you go into the ring.

When you say show lead technically it's just another lead that is easy to fold up
into your hand and is comfortable and if you mean
Border Collies a friend used to show hers on a fine half rolled leather check
collar and rolled leather lead.
You don't normally leave the 'ordinary' collar on as well as the show one as this spoils the outline & look
of the dog
With Boxers they tend to be shown on choke chain and leads. When not shown mine have half leather
check collars that they wear around the show ground but in the ring they are on the show choke chain..
Hope this helps
:)

Thanks for the replies. Will have to go and buy a slip lead to match his choc/red coat. Yes he is a Border Collie. :-) Going to his first open in December in Maidstone, Anyone else going?