Cattlin 2.5 years mine-life, page-44

160,000 tonne per annum @ 5.5% concerntrate or equivalent to 2,909,000 tonne per annum @ 1.0% concerntrate

at 50% of indicated + 100% of measured = (50% * 9,534,000) + 2,540,000 = 7,307,000 tonne

7,307,000 / 2,909,000 = 2.52 years

Note: Production guidance is not 160t, it's 160kt (note the k)
Note 2: indicated and measured has slighly higher concentrate than 1% so.. maybe 2.6 years.. but 2.5 is an easy number to remember.