
Firstly, I don't think celebrities will intentionally ignore some people's letters and reply to others. They don't know who you are personally, and will not pick and choose whoever they wish to reply to.
You mentioned earlier that you had seen 3 successes from the address you sent a letter to, including one that was sent the day after yours. Perhaps Clive was responding to mail he received up to a certain date. Given the time it takes a letter to travel overseas, could the other mail that was sent a day after yours arrived earlier? With any mail that he didn't respond to, he probably would still have it (either with an assistant or whomever,) so don't worry! He'll probably go through it eventually.
However, did you send an SASE (SAE & IRC's) along with your letters? Sometimes celebrities won't return anything unless you've actually sent one with your request. You did mention semi-SASE...what do you mean by that?
It doesn't hurt to try again. Third time might be lucky for you
All the best Lucas.
nowandagain [rockon]