Isn't the Hartest chevron part of the Newmarket Ridge? I climbed it once on a ride with Annie and my front wheel was lifting each time I pressed on the pedals.
The highest point (420', also Suffolk's County Top) is near Rede, in a wood. The road just exceeds 400' and the climb from the Stour crossing at Glemsford, through Hawkeden (stop for a pint at the Queen Victoria) up to Rede is about as un-East-Anglia-like a ride as you'll find in East Anglia. These are not the sort of roads on which to take NSTN unless you remember to pack you profanifilter.
It's a great descent from the summit towards Mildenhall because it's so long, but at that point it's nowhere near as steep as North Hill.