Following information from wikipedia.org/wiki/Chesterfield
The spire was added to the 14th century tower in about 1362. It is both twisted and leaning, twisting 45 degrees and leaning 9 feet 6 inches (2.90 m) from its true centre. The leaning characteristic was initially suspected to be the result of the absence of skilled craftsmen (the Black Death had been gone only twelve years prior to the spire's completion), insufficient cross-bracing, and the use of unseasoned timber.
However, it is now believed that the twisting of the spire was caused by the lead that covers the spire, which was added 300 years after it was built — before this it was covered with oak tiles. The lead causes this twisting phenomenon, because when the sun shines during the day the south side of the tower heats up, causing the lead there to expand at a greater rate than that of the north side of the tower, resulting in unequal expansion and contraction. This was compounded by the weight of the lead (approx. 33 tons) which the spire's bracing was not originally designed to bear. Also it was common practice to use unseasoned timber at the time the spire was built as when the wood was seasoned it was too hard to work with, so as unseasoned wood was used they would have made adjustments as it was seasoning in place. These theories can be rejected as there is evidence to suggest that the spire was straight for the first 300 years after it was built and as wood seasons within 50 years these theories now can hold no weight.
In common folklore, there are numerous explanations as to why the spire is twisted. One is that the spire was so shocked to learn of the marriage of a virgin in the church that it bent down to get a closer look. Should this happen again, it is said that the spire will straighten and return to its true position. Another is that a Bolsover blacksmith mis-shoed the Devil, who leaped over the spire in pain, knocking it out of shape. Many other such stories exist, these are two notable examples.