I was also there at your first Ashes match at Wembley in 1963. Was working in London and helped to organise ( via the company's Sports and Social Club) a coach trip of over 2 dozen to see the match - for most this was their first visit to a RL game and they really enjoyed the floodlit game even though there was only a crowd of around 14,000. At least, unlike you, we were under cover!
I was pretty optimistic going into the match as we had won the 2 previous Ashes series in Aus(1962) and the UK(1959) and the atrocious weather was in our favour too but we were completely outclassed as you described. Ever hopeful I went to Swinton to see the second match and we conceded 50 points in a complete shellacking.