The double header will be the first time since 1997 that 'international RL' has been played at Wembley (I didn't use the word "test" since that '97 SL test isn't recognised as an official test match by the ARL). We've had to wait 14 yrs since then. It'd be a massive shame if the ground was less than half full (45000), and this subsequently led to the RFL shafting Wembley for goodness knows how many more years. For me, barring bad weather, 45000-50000 should be the absolute minimum for this occasion and anything more than that is a huge bonus. Hopefully this will lead to more matches at Wembley (the next one should be the 2013 RLWC opener between England and Australia, since they are drawn in the same group for the WC). And no, my expectations are not high. I'm not expecting us to get 80,000 that the Challenge Cup Final usually gets, because the CC is a prestigious event with more than 100 years of history. Not to mention that 15000 of the 90000 seats are for the reserved corporates, nearly all of whom would only turn up for the soccer.
On the topic of Australia vs England/Great Britain matches in London, the last time this occured was back in the 2000 RLWC. I believe all other Australia vs England/Great Britain since then have been held in the north of England. Despite the fact that the 2000 RLWC was an absolute disaster (both financially and weatherwise), the lacklustre England/Australia opening match at Twickenham still got 32000 ppl. I'd love to think that with the vast improvement in international RL since then, that we'd get a lot more than 32000 in a fortnight or so time at Wembley