@whimsy
ok. first i'm extremely sorry if my toot read with a scolding tone. very sorry i appear to be on one this evening.
the answer about the teabag shape is I don't know. if circular or pyramid teabags had been protected as a trade mark, no one else would be able to use them but it doesn't seem PG Tips or Tetley went for those protections for their relevant bags. both would remove the need to tear open 10% of your bags when making tea.
I assume yorkshire tea would read your email if you asked them about their design decisions.
@whimsy
the really laughable bit, for a student of IP rights. if they had made no claims for the functionality of pyramid bags they could have protected them as a trade mark, which is indefinite protection on paying a small renewal every 10 years. once you claim your tea bag is a functional innovation you can only protect it as a patent which has a 20 year limit and is very expensive.
Ritter Sport have a trade mark on square bars of chocolate, everyone else has to make oblongs or other shapes for their chocolate.