Green’s Dictionary of Slang

teaich-gir adj.

also teatchgir
[backsl., pron. ‘tadger’]

right (quality, not direction).

[UK]Sl. Dict.
[UK]Farmer & Henley Sl. and Its Analogues.
[UK]J. Ware Passing Eng. of the Victorian Era 241/2: Teatchgir (Coster). Right.