"Our logic was to do the right thing for our customers which we believe there was no reason not to pass on that 25 base point cut to our customers. We didn't deliberately set out to be first, it was just out of the process that we normally do. It just so happens that others were slow rather than we were quick, I think," he says.
"We are small and nimble though. So we can, when we're surprised, we're able to get the people together quite quickly and make a good decision without having to go through a bureaucratic system which might take days.
McLachlan has described the OCR cut by the Reserve Bank Governor Graeme Wheeler as a "deliberate action to surprise the market."
"Why? He knows a bigger reaction will get the currency down. He's really desperate to get that down which is the key for him to re-balance the things he needs to get inflation to the level that's within his band."
The currency was important to Wheeler, McLachlan says.
"First of all it's about dealing with external balances between exports and imports. Certainly with our dairy price coming down so far that impacts our export. There's a risk that there needs to be a balance in that current account. So they would the really like the currency to be an offset to the dairy price fall.
"Secondly an over valued exchange rate depresses local prices. So one of the things that is keeping that, is keeping inflation below the bottom end of his band."
McLachlan says this week's cut will only strengthen the housing market.
"My personal view is the housing market is as strong across New Zealand as we've seen it for a very, very long time. Prices there are anecdotal stories everywhere which are not yet in the data. The market is incredibly strong and I think this is going to fuel that even more.
"The stock of houses is really low. Demand is really high and there is only one thing that can give and that's the price and that's what's happening," he says.