I've never yet been refused a transit by East Mids who are one of the most friendly and helpful ATC units I've come across. Well done guys & girls!
I've only ever tried to go through Solent zone on two occasions - on the first they were helpful and accommodating at FL40 right over the top of SAM, whereas on the second they flatly refused me ANY transit and basically said go away. There may well have been genuine workload reasons for this but the frequency was far from busy and another VFR transit was granted to someone else just 2 mins. later on a similar track. I routed around and below their zone to east and they dumped me the moment I hit the coastline.