Editing Openai/69186d20-2d14-8013-b9c6-c09000f173f6 (section)

==== The standard genealogical picture you actually want in your head: ====
# Continental Celtic (all extinct) - Gaulish (P-) - Lepontic - Celtiberian (Q-) - Galatian (in Anatolia)
# Insular Celtic (survivors + some extinct) - Goidelic (Q-Celtic) - Irish - Scottish Gaelic - Manx - Brittonic (P-Celtic) - Welsh - Cornish - Breton

Within Insular Celtic, there’s also a strong view that all Insular languages share innovations beyond P/Q (syntax, verbal periphrasis, mutations, etc.), so many linguists treat Insular Celtic itself as a real subgroup, and P/Q as a secondary isogloss inside it plus its Continental echoes.

A related proposal is Gallo-Brittonic:
* Gaulish + Brittonic share various extra traits (including P-feature) → some people posit a Gallo-Brittonic subgroup (Gaulish + Brittonic) vs Goidelic + Celtiberian as another cluster.

So your hierarchy of “types” looks roughly like:
* Celtic - Insular Celtic - Goidelic (Q) - Brittonic (P) - Continental Celtic - Gaulish (P), Celtiberian (Q), etc.

with P/Q running diagonally across.