Speed Limit signage poorly placed

On the approach into Charlbury on B4437 the 20 mph sign is not visible to motorists until they are approximately 20 yards from the sign. The two photos attached refer. Motorists would need to brake hard to reduce speed from 30 mph to 20 mph with such short notice. There is also a concealed public footpath that crosses the road between High View Lodge & Ansgar House over the road then between Park View & Kimber Cottage. The public footpath signs are not visible to motorists. This footpath falls in the 30 mph speed limit. The road also narrows considerably due to hedges either side of the road which makes it extremely difficult for vehicles to pass each other safely and no refuge exists for pedestrians. Would it be possible to relocate the signage in question to a verge near to Kantara? This would give drivers to and from Charlbury a better visible warning of the speed limit change whilst protecting pedestrians using the public footpath that crosses the road and those walking on the most dangerous stretch of the B4437.