A classic "behavioral finance" mistake investors make is anchoring on the purchase price of a stock and letting that drive the hold/sell decision. What you paid for the shares is irrelevant at this point (the purchase price is a sunk cost - you can't get it back no matter what, so it can't affect your decision today)
Assuming you would purchase a different stock if you sold the Barclay's shares, the only question to consider is: if I had this amount in cash today, would I buy Barclay's or some other stock? If some other stock, sell. If Barclay's, hold. Two mitigating factors: 1) transactions costs to make the trades 2) any taxes owed on the sale of Barclay's. Both these would have you holding Barclay's all other things equal.