Purim Katan in Yerushalayim

Question

The Mishnah Berurah (497,14) writes, based on the Pri Megadim, that Purim Katan is on the fourteenth of Adar Alef even for krachim mukafim (cities with a wall from the time of Yehoshua ben Nun); not on the fifteenth of Adar Alef. But in the Halichos Shlomo (Ch. 19 Hilchot Purim, footnote 28), it is brought from the Rav’s father, Rav Shlomo Zalman Auerbach zt”l, that in Yerushalayim, Purim Katan is held on the fifteenth of Adar Alef, and not on the fourteenth as the Mishnah Berurah wrote. Please clarify.

Thank you,

Yehuda Korolnik, Yerushalayim    

Rav Auerbach 

Here in Yerushalayim we keep certain customs called ‘minhagei Yerushalayim’. The fact is that we celebrate in Yerushalaim Purim Katan on the fifteen of Adar Alef. It could be that this is one of the minhagei Yerushalayim, but I cannot tell you this. And to ask my father what he meant by what is written in the Halichos Shlomo, I also can’t do anymore. We have to know that the Mishnah Berurah was written for the general world, and probably did not address all of the minhagim which are kept in Yerushalayim.