In the early summer of 1463, Sir Ralph Percy reverted to his former Lancastrian loyalties and surrendered Bamburgh and Dunstanburgh to the Scottish/Lancastrian allies. In its way, trusting Ralph Percy with this responsibility had been as big a gamble as trusting Somerset, but it may have been the case that he was the only practical option in this neck of the woods, where the Percy name was still important.
Perhaps more surprising was the decision of Sir Ralph Grey to hand over Alnwick to the enemy. Grey had been regarded as a committed 'Yorkist' and was indeed grandson to the Grey executed with Cambridge at Southampton in 1415.
Warwick and Montagu were immediately instructed to mobilise their forces in the north - Warwick had been in London for the Parliament and had to make a long journey. Edward meanwhile concluded the Parliament without any undue haste and moved to Northampton, where he planned a muster.
Somerset was very much in his company - but the men of Northampton remembered the damage to their town caused by the Lancastrian armies a few years before, and rioted against the duke, even though he was in King Edward's proximity and surrounded by the King's guards. Edward had to break up the 'scuffle' with his own hands, rescue Somerset and threaten the rioters with a swift hanging if they did not disperse. The angry citizens retreated to their homes, and Somerset was saved.
However, Edward decided that he could no longer be kept about his person while emotions were so high against him. He sent Somerset (with a suitable guard) off to North Wales. Accounts differ as to whether it was to Chirk or Holt. I suspect the latter as the Duke of Norfolk was established there, with the difficult task of keeping order among some fairly restless local punters. This Norfolk was not the one who fought at Towton, but his young son, an individual who was always to prove a loyal Yorkist, albeit not a particularly capable one. He was probably employed at Holt as he was the only magnate available for the task with lands in the strategic area, not because of his great ability. But his wife, Elizabeth Talbot, was first cousin of Somerset and of course, sister to the legendary Lady Eleanor Talbot! I believe Somerset was sent to stay 'with family'. Given that the area was riven with Lancastrian dissent, it was not an obvious place to send someone Edward suspected might choose to defect. This leads me to think that Edward still had faith in Somerset.
The Nevilles meanwhile relieved Norham Castle and Newcastle, but were not in a position to recapture the lost castles. In August Margaret of Anjou and a small party set off for France again, hoping to secure more aid from King Louis. Whatever faults Queen Margaret had, no one could accuse her of being a pessimist.