COFFEE and cake is a cut-throat business at Samford Village, northwest of Brisbane.

Black Sheep Cafe's Markus Konrad Hermann appeared in Brisbane Magistrates Court this morning, pleading guilty to breaking a key in the front door lock of competitor, The Happy Berry House.

The Happy Berry House is in Samford's Main Street, next door to the cafe where Hermann, 45, worked and lived with his family.

Police prosecutor Sgt Paul Hodges said the broken key jammed in the lock prevented the owner of the Happy Berry House from entering the business.

Sgt Hodges said Hermann told police he wanted to break a key in the lock to "annoy the informant".

He said Hermann appeared to go to the Happy Berry House twice, breaking the key in the lock successfully the second time, at 8pm on October 22.

The incident was captured on CCTV, he said.

Magistrate Linda Bradford-Morgan fined Hermann $300.

Outside court, Hermann told The Courier Mail he'd been drunk at the time and he was sorry.

"We struggled to get it (Black Sheep Cafe) up and going and money has been an issue for us," he said.

"Next door doesn't struggle with money like we do and they get people in with these two-for-one deals.

"It's just very frustrating but I made a huge mistake."

Originally published as He's the caf-fiend of Samford cafe society