britanizar

A rare, mostly journalistic or academic neologism meaning to make British in style, custom, or institutions — coined by analogy with americanizar and europeizar rather than a word most native speakers use in daily conversation.

• Algunos críticos dicen que el proyecto quiere britanizar la política local. — Some critics say the project aims to make local politics more British.
• La colonia se fue britanizando con el tiempo. — The colony gradually became more British over time.
• No hace falta britanizar cada costumbre para modernizarse. — There's no need to Anglicize every custom in order to modernize.

This word is rare enough that most native speakers would understand it by analogy but rarely produce it themselves — anglicanizar/anglizar are occasionally seen too, with no single standardized form.