Green’s Dictionary of Slang

a starched cravat; a stiff white tie.

1818		‘One of the Cloth’ [bk title] Neckclothitania or Tietania: being an essay on Starchers.
1853		R.S. Surtees Mr Sponge’s Sporting Tour 3: If [he wore] a striped waistcoat, then the starcher would be imbued with somewhat of the same colour and pattern.
1890–1904		Farmer & Henley Sl. and Its Analogues.