Utility costs are very different in Sydney and Oxford. Overall the UK is more expensive, even at current exchange rates.
Our electricity consumption here in Oxford - over six months of summer - is about 2/3 what it was in Sydney. This is probably because we have fewer desktop computers running 24/7, and no microwave. Our electricity bill, however, is almost exactly the same (at an exchange rate of 0.59/1.7) — the per kilowatt charge is almost the same in pence as it was in cents!
Our gas bill in Sydney ran to about $120/quarter. Here it's going to be much more seasonal, but looks like it will average more than £150/quarter over the year, or twice as much. That's hardly surprising, given we have gas-powered central heating. (There's a reason UK pensioners get a special heating allowance in winter.)
Both houses have fixed water charges; neither has a meter. In Sydney (where the landlord pays the fixed water charge) we're paying about $130/quarter for water but in Oxford (the tenant pays in the UK) we're only paying £19/month (about $100/quarter). In Sydney we're paying $140/quarter for sewage and storm water; in the UK those are covered by the council rates.
The council rates here are much higher — and in the UK the tenant has to pay them! We're paying something like £1800/year in rates, while in Sydney we are paying less than $1100/year. These numbers aren't really comparable, however, as the council here funds the county police force and provides other services handled by the state government in Sydney.
Our combined Internet and fixed phone line was $76.50/month in Sydney (from Internode). Here in Oxford we're paying about £10.50/month for a basic BT phone line and £23/month for Internet access (from Be). Not only is that cheaper, but the Be plan appears to be genuinely unlimited, whereas we had a quota in Australia which we never reached but which we had to keep an eye on.
Conclusions: (1) Utility costs are higher in the UK, overall, and would be much higher at more "normal" (historical) exchange rates (or in comparison to wages). (2) Letting a house in the UK while renting in Australia would be a better deal (and on top of the water and rates asymmetry, residential property in the UK has much better rental yields).