English Football - Animals on the Pitch?

It's customary nowadays for the manager of the winning team to run onto the field to congratulate his players after the final whistle. 

Not so for England manager Alf Ramsey in 1966 - he did run onto the pitch following the stormy England-Argentina quarter-final, but not to celebrate. 

Instead, he rushed to make sure his players wouldn't swap shirts with the Argentinians, saying "We don't swap shirts with animals!"