I've had folk tell me my name is quintessentially English. It isn't. My forename is Hebrew and my surname is Welsh. Not many know I am Welsh originally but, before talking for the first time, I've had English people approach me for a chat purely because my Wales shirt interested them.
Welsh nationalism does exist. I know Welsh people who switch from speaking English to their mother tongue when outsiders are around purely so they can't understand what is being said.
A woman on my team at work's husband is Welsh and I've been introduced to him and his mates whilst they were out in Manchester. They all have a real dislike for the English, especially the football side and it's fans.