Queensland Investment Corporation has not marked down its valuation in struggling Thames Water, the heavily indebted London utility staring at the prospect of a break-up or government-led oversight.

The Queensland government’s wealth fund owns 5.4 per cent of Thames Water, once part of Macquarie Asset Management’s portfolio. Thames Water’s major shareholder, Canada’s OMERS, in May wrote off its entire 31.7 per cent stake in the business.