its been widely accepted Jesus was born in the Summertime) - my source for this QI.
I think 'widely believed' might be more accurate. There's a substantial body of credible opinion - probably wider than the summertime theory in fact - that puts doubt on the historical existence of the Jesus Christ character mentioned in the gospels.
There are no contemporaneous accounts of his life, much less his supposed birth - strange for such a supposedly influential person. The existence of St Paul and of the Nicean Council is pretty well beyond doubt. The support for their 'histories' of the Jesus Christ figure is at odds with reputable historical research, both of their day and of the present. In other words, he was, a religion, that's all. (No offence intended to individuals' beliefs, but hopefully a little tolerance for one of the mainstream scientific / atheist beliefs may not be out of place.)
Most of the miracles can be found word-for-word in historically antecedent texts. There are numerous religious figures with the same life story of virgin birth and miraculous return from the dead. Most of them have thankfully died out, but they didn't have the clout of the Roman Catholic Church. Some of the gospel texts are accurate and truly spiritual - ones apparently copied from earlier texts without being muddied. A bit like the way the Psalms stand out as a remarkable composition of the OT - amidst legends and fantasies of torture and nastiness invented by sick sad priests.