[Tigers] Lucas dashboard switches

[Rollright at aol.com]

Hello,
 
I purchased a box of English car electrical odd and ends, (e-bay) mostly  
junk.
 
But, I got about 5 dashboard switches in various condition. A couple of  
them had a wavy very narrow, very thin copper (?) washer between the round  
slotted nut and the body of the switch, falling over the threaded part.
 
In all my 34 years of ownership and switch-fiddling, I've never seen one of 
 these. 
 
Are they supposed to be used on all our toggle switches? And if so, where  
could I get more?
 
 
Jim  Armstrong
Mk 1A 382002083
LRXFE