I wanted to win this but I failed to realise the intense competition. This eventually sold for around GBP48.
Historically and philately, if there is such a word, this a very important stamp and postmark. Muara up to 1921 was administered by the Brookes. This include the postal service using stamps from Sarawak. Sometime before 1921 the Brunei postal service started there. So this postmark showed that at least by 1914, Sarawak stamps were no longer in use in Muara.