Gail Kelly was coy when asked if Westpac would follow the Commonwealth Bank and raise its mortgage rate. Source: AP

The matriarch of Australian banking says a deep structural shift is playing out in the banking industry and the cheap funding that was a hallmark before the global financial crisis is gone forever.

Unveiling a cash profit of $5.88 billion yesterday - taking the combined profits of the "big four" banks to a record $21.7 billion - Ms Kelly was coy on Westpac's plans for mortgage rates.

She refused to be drawn on whether it would follow its chief rival, the Commonwealth Bank, in hiking mortgage rates beyond the Reserve Bank's latest increase in the official cash rate.

But she repeated the mantra that banks were paying dramatically more for wholesale funding - cash borrowed from institutions around the world to lend to Australian consumers - relative to the Reserve rate.