We looked into this exhaustively and I agree, it's confusing.
If you're over 60 and take money from your Australian super fund, it gets special treatment, and is not taxable in Australia - as you know. If you have moved to the UK, any money you draw from your super is classed as income. It gets no special treatment.
To quote:
"The general rule is that where double taxation agreement is available, the country of the pensioner's residence has taxing right in relation to pensions sourced from another country. For example, a UK resident receives an allocated pension from an Australian fund. No tax is payable by the Australia fund, tax on the pension is payable instead by the pensioner in the UK."
http://www.ngssuper.com.au/assets/Downloads/Retiring-Overseas.pdf