"Egyptian mules" could be an allusion to the siege of Khartoum, capital of Sudan. The Sudan was a dependency of Egypt, which in 1882 was invaded and occupied by the British to safeguard their strategic interests. The city was defended by an Egyptian garrison under the British general Charles George ("Chinese") Gordon. [i] Alternatively 'Egyptian' could mean 'gypsy' although the last usage in that sense cited by the OED is dated 1749. [ii]

References:
[i] https://www.britannica.com/event/Siege-of-Khartoum (accessed 25Nov20)
[ii] OED

The Birmingham Daily Post 23 December 1885 p4 reported -  "We have published lately many letters on the subject of steam tramcars, and the various grievances alleged against them...[it is alleged that] they emit smoke and steam to an annoying extent ... the noise caused by them and the shaking of the ground result in the depreciation of the value of house property...Just now, in one district of Edgbaston in particular... there is an active scheme of resistance put in operation."

Food parcels from home were a noted feature of life in private schools - sharing his cake would have helped young Gilpin to make friends. Likewise, the gift for the master was offered in the hope that the boy would be well treated. Boys were often badly treated by their fellows and masters - a phenomenon discussed in popular novels of the 19th century, notably by Charles Dickens in Nicholas Nickleby (published 1838/9) and later by Thomas Hugh's in Tom Brown's Schooldays which was informed by his own schooldays during 1834 to 1842

The prevailing winds in Britain are from the south west. Affluent suburbs were built to the west of cities so that the prevailing wind would blow smoke toward the east - where the poor lived.