Hey guys..... never used this site before but I hope someone can help me...

Im looking to book a Reward seat going to NYC between 23rd May - 30th May 2019. I live between LBA and MAN so as I plan to use a Lloyds Avios Upgrade Voucher looked to fly from those airports via LHR. But im confused.

LBA-LHR-JFK on the above dates looking to be 110,000 Avios + £660.19 - However, there are only 2 options available with one being an 8 hour stop-over at LHR or the later being 1.25 hour stop-over.. neither ideal

MAN-LHR-JFK on the above dates looking to be 110,000 Avios + £835.46 - Times are much more varied and better but why the hell is it £175.27 more expensive to fly from MAN than LBA

I have made sure the LHR-JFK-LHR flights are the same using BA0183 outbound and BA0174 inbound, both of which are BA metal.

I've even looked purely at the domestic flights. To travel from either MAN or LBA to LHR is the same price and Avios....

SO WHY IS IT £175.27 MORE EXPENSIVE to fly from MAN than LBA?????

Thoughts and comments welcome. Thanks in advance....