It wasn't quite the debut to cherish as the RaboDirect PRO12 side fell to a 34-16 defeat at Rodney Parade against their English opponents.
And what's more Mills had to scrummage in standing water in front of the North Terrace towards the end of the game, as the heavens above opened.
But Mills insists the experience has far from put him off, quite the opposite with the 24-minute run out leaving a lasting impression in the front rower's mind.
"The learning curve was steep and it was great to gain a lot of experience and pick up technical skills through the week," Mills told the South Wales Argus.
"It was a hell of a game to make my debut in, especially with the weather. The Northampton tight five was so strong and it was a bit daunting, but it was nice to get out onto the pitch and I enjoyed it.
"It's given me a taste of regional rugby and now I've got to go back to Bedwas and keep learning.
"It was nice to see what's involved in becoming a regional player. The training was hard but it was a great experience and I learnt more last week than I have in a long time."
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