What's a GILT/Treasury Stock?
Gilts are bonds issued specifically by the British Government. A conventional Gilt will pay you a fixed cash payment every 6 months until maturity, at which point you will receive your final payment and the return of the initial investment.
You can sell corporate/government bonds at any time, and because prices go up when interest rates fall, modest capital gains are possible. These gains are tax-free on Government bonds and some corporate bonds. Interest earned is usually taxed, unless bonds are held in an Investment ISA.