"And on the sixth day, God created Manchester"
Gods own City, and there can be no doubt.
As for the tree, yes, you took too much off the top and that was the start of the problem as in simple terms, the tree still has a root system that was developed for the size of the tree that it was before you topped it. The result is that it will now have a series of hormonal triggers to redress the imbalance and this process of mending itself can cause a variety of other stresses to come into play as the healing process will take a lot of energy. In short, you shouldn't have topped it - but that is done now so you will have to live with it.
The comments about a good, treated, organic mulch around the base of the tree to the drip-line and an irrigation regime are spot on, as I think the tree looks drought stressed too. Even the comment on it being one sided as a response to wind affect is also entirely plausible. Do you know the predominant wind direction in your area or is there a possible funnelling of wind between buildings perhaps?
As for the cracking, these simply look like growth cracks to me which are common in the species. As you know, trees grow in annual rings (mostly) and for the newly formed wood underneath to be able to overlay the previous years growth, something has to give which causes the cracks in the bark. You can see it much easier in some species then others, and I think that is what you are seeing here.
Other then the suggestions made in the comments above, I think you will be doing all you can. Perhaps a final note on the watering though, the watering shouldn't be absolutely hammered at the base of the tree, as the main area that trees suck up water from is more towards the root tips where the fine root hairs are, so a distributed watering perhaps from a wide area garden sprinkler may be better - but still mulch and keep the mulch moist through the summer.
Best of luck with it in any case.