Past work for the Middlesex-London Health Unit (MLHU) by embattled political consulting firm Blackridge Strategy is now under the microscope.

On Thursday, CTV News obtained an invoice through the Freedom of Information Act that reveals the MLHU paid about $4,100 last summer for "advocacy" with three provincial ministries and the premier's office.

The goal of the advocacy was to extend provincial funding for the temporary overdose prevention site at 186 King Street.

MLHU medical officer of health, Dr. Chris Mackie says, “We were looking for someone to open doors and build relationships, and yes, I would consider that government relations or lobbying.”

London North Centre MPP Terence Kernaghan has questions about the advocacy.

“What did they discuss? Who did they meet with? And when did that happen?”

But searching for Blackridge Strategy on Ontario's lobbyist registry reveals only four entries, none related to the health unit.

Searches for past and current principals at Blackridge yield no additional results, and the MLHU does not appear as ever being a client of a registered lobbyist.

According to a statement from Ontario’s Office of the Integrity Commissioner, the online search tool is comprehensive.

"This includes all registrations, active and inactive, that have been received since the registry was created in 1999."

Kernaghan says since public dollars were spent for Blackridge's advocacy work, the public deserves answers.

“This whole situation is a mess, it stinks to high heaven. Here we have a situation where we have unregistered lobbyists meeting with the premier's office.”

Blackridge Strategy is the same London firm that has defended anonymous election websites attacking Councillor Maureen Cassidy and former councillor Virginia Ridley as “harsh” but “factual.”

Ontario's integrity commissioner investigates complaints for violating the Lobbyists Registration Act and violators can be forbidden from lobbying for up to two years.

CTV News has repeatedly asked Blackridge to explain why last year's work for the health unit can’t be found on the provincial lobbyist registry, but has so far received no response.