Hi OP
We were looking for a property around that size and budget in and around your area up until a month or so ago.
On the positives I would say good area, lovely garden and great kitchen.
The things I don't like are probably not things you can change but it may help give context. As one poster said above there is no 'wow factor', either architecturally or decoratively. The period features are nice esp in hall but not amazing and whilst it looks well maintained the decor and furniture is dated, so it doesn't scream modern family home. I also think the layout isn't the most practical or lovely big rooms but no where really for a play room or study downstairs.
My guess is that buyers like it but don't love it enough to stay committed either because they find something else or because they realise they would want to spend ££££ taking out the conservatory and putting an extension in with bi fold doors, converting loft, garage etc. Looking at the under offer and sold in your area similar properties do seem to have more wow/character/easier floor plan.
On dropping price, or excepting lower offers, it's your call but dropping it by less that 5% would seem pretty pointless, if it's been in the market that long, we had estate agents telling us that buyers were accepting offers 20% under asking. I would probably take it off the market for a couple of months and put back on in March with the second set of photos.
If you're kicking yourself re Brexit, I feel your pain we bought our first house months before the last financial crisis and on a long term fixed rate mortgage! We kicked ourselves for a long time but ultimately it has been a home not an investment and we have still made good money on it - it's pointless comparing ourselves to others !