The entire staff were on deck and after shifting everything upstairs, they left the building about 7.30pm.
"Then it was just a question of waiting to see how bad it actually got," Mr Anderson said. "No one was quite aware of how significant the outcome would be."
In the end the water and silt made it all the way through the gallery, ruining the flooring and walls.
It was Thursday before staff could get back in.
"Our staff were put to work on the various elements of the council relief effort. So some were on the phones, others packing food parcels. Basically we were on hand to fulfil any kind of requirement.
"The staff worked constantly, as did all the council staff. It was a pretty heroic effort."
Sarjeant on the Quay was closed until September for repairs.
"We'd put a lot of effort into making this place successful, then it was all over in a night," Mr Anderson said.
"So we had to come back from that, but that's nothing compared to the magnitude of those individuals and smaller businesses around here who had to come back from that or didn't have the wherewithal to do it.
"All things considered, we got off relatively lightly."
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