Well since they are over 170 years old - they look pretty good to me.

I am sure it is environmental - acid rain, freeze thaw, etc.

 

Water freeze/thaw.  (Hint, look at bottom of eave)

That looked like cast-in-place concrete that wasn't that old and it looks like shrinkage cracks.  Was there a repair band done on the column at some time?

They don't look like shrinkage cracks to me. I find it interesting the section above and below are not cracked. I had something similar looking on a 50 year old building. At each location where this cracking occurred there were drainage problems nearby. I could only assume the freeze/ thaw cycle caused it. However if there is rebar or wire in the column, then corrosion due to carbonation can cause that kind of cracking. That is common in older parking deck structures.  

www.idecharlotte.com

Is it just me or does the pattern of the cracking looks similar to some reinforcing or mesh close to the surface? If the building is that old and it has just recently occurred, I would suspect carbonation.  

It has been very cold in Britain in the last few weeks, increasing the possibility of freeze/thaw.  Are the cracks recent?

yes the cracks are recent (last few years), i beleive it may be from the repair that was done to the building after an old victorian extension was demolished. Many thanks!

OP refers to stone pillar.  If it is limestone rather than concrete, weathering deterioration is probably just due to differing quality of original stone.

i am also debating with my collegue over the deterioration of the eaves, do you believe it is a result of freeze/thaw damage or from suplhate attack from acid rain? i personall think it may be a combination of both.

Any ideas?

I agree with Ron. To me, the crack pattern looks like a concrete repair that was made with either the wrong patching material or the patch was not properly installed.