gloopy
When I hada repair done the other year it was a "rubber mushroom" fitted from the inside with plenty of rubber solution under the head against the inside of the tyre. Excess "stalk" was simply cut off.
I think I have the Dunlop tyre repair kit my Dad had from the 60's.
1/4" or so dia rubber cylinder, rubber solution and a tool to thread it through the tyre. Don't think I'd trust that sort of repair these days.