The East London Wonderland was on the opposite side of the road to the Pavilion Theatre and can best be summed up by an article from H. Chance-Newton on the East End Music Hall. It was written in 1902.

“To those amusement-seekers who may prefer to take their variety entertainment in a rough-and-ready form there are still such haunts as that Whitechapel resort fancifully named “Wonderland.” In this big hall are provided entertainments of the most extraordinary description. They include little plays, songs, and sketches, given first in Yiddish dialect and afterwards translated into more or less choice English by, as a rule, a Hebraic interpreter. This interpreter often improves the occasion by calling the attention of kind – and mostly alien – friends in front to certain side shows consisting of all sorts of armless legless, skeleton, or spotted ” freaks ” scattered around the recesses of this great galleryless hall. When once the “freaks” have been examined, or the “greeners” and other foreign and East-End “sweated” Jew toilers have utilised the interval to indulge in a little light refreshment according to their respective tastes, the Yiddish sketches and songs – comic and otherwise – are resumed until closing time.
“It is, however, on its Boxing Nights (which in this connection means Mondays and Saturdays) that “Wonderland” is to be seen in its most thrilling form. Then it is indeed difficult either to get in or to get out. In the first place it is hard to get in because of the great crowds of hard-faring – often hard-faced – East-End worshippers of the fistic art; several types of which are to be seen in our photographic illustration on page 223. In the second place, if you do contrive to get in you speedily find yourself so hemmed in by a sardine-like packed mob that all egress seems hopeless.”

For full article see this site on Victorian London – as with many I have found if you are interested in the subject it’s Dictionary of Victorian London – Here is the direct link to page