A quick check of their 2011 annual report shows the following:
http://www.advent.com.sg/files/SXR_AR2011.pdf
Twenty largest holders of quoted equity securities and depository receipts
Name Number Percentage
Apollo Nominees Ltd <CRE> 15,476,153 7.73%
Citicorp Nominees Pty Limited 13,377,538 6.68%
UBS Nominees Pty Ltd <PB SEG A/C> 13,340,403 6.66%
Credit Suisse Securities (Europe) Limited 12,107,440 6.05%
Fitel Nominees Limited <0061403> 10,921,867 5.45%
Hargreave Hale Nominees Limited <LON> 9,798,988 4.89%
Chase Nominees Limited <Artemis> 9,000,000 4.49%
National Nominees Limited 7,025,004 3.51%
Fitel Nominees Limited <0067873> 7,000,000 3.49%
UBS Wealth Management Australia Nominees Pty Ltd 4,700,000 2.34%
HSBC Global Custody Nominee (UK) Limited <993791> 4,500,000 2.24%
Queensland Investment Corporation 4,215,029 2.10%
Smith & Williamson Nominees Limited 3,732,000 1.86%
Fitel Nominees Limited <0070851> 3,173,743 1.58%
L R Nominees Limited <NOMINEE> 2,906,907 1.45%
Pershing Nominees Limited <SKCLT> 2,774,901 1.38%
HSBC Global Custody Nominee (Australia) Pty Limited 2,688,896 1.34%
Barclayshare Nominees Limited 2,556,980 1.27%
TD Waterhouse Nominees (Europe) Limited <SMKTNOMS> 2,410,229 1.20%
Mr Robert Jeffries Chatfield 2,400,000 1.19
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Looks to be mostly institutional investors, really. They paid 27% of their profit in tax, so probably most of it was taxed at source in Australia, then remitted to Singapore.