A surgical instrument, the surgical instrument comprising: a handle comprising first and second handle portions (102, 104), one of the first and second handle portions (102, 104) comprising a proximal latch and the other of the first and second handle portions (102, 104) comprising a proximal latch pin, the proximal latch and proximal latch pin being configured to engage with each other to lock the first and second handle portions (102, 104) pivotally together at proximal ends thereof, wherein the second handle portion further comprises a latch projection, and the first handle portion further comprises a clamp arm, the surgical instrument being characterized in that the first handle portion further comprises an over center linkage pivotally connected to the clamp arm at a first end and slidably connected to the first handle portion at a second end, the latch projection and over center linkage being configured to engage each other when the clamp arm is depressed to lock the surgical instrument in a closed position in which the handle portions (102, 104) are clamped together in proximity to each other; wherein depression of the clamp arm causes the second end of the over center linkage to slide relative to the first handle portion from an unengaged position of the over center linkage to an engaged position in which the over center linkage engages the latch projection, wherein the first handle portion further comprises a clamp arm release slidable between engaged and unengaged positions and biased towards its engaged position, wherein the clamp arm release is retained in its unengaged position when the over center linkage is in its unengaged position and wherein the clamp arm release is permitted to move to its engaged position once the clamp arm has been moved to its depressed position, and wherein the clamp arm release is configured to retain the over center linkage in its engaged position and the clamp arm in its depressed position when the clamp arm release is in its engaged position and to permit the over center linkage to move to its unengaged position and the clamp arm to its undepressed position once the clamp arm release has been returned to its unengaged position. a handle comprising first and second handle portions (102, 104), one of the first and second handle portions (102, 104) comprising a proximal latch and the other of the first and second handle portions (102, 104) comprising a proximal latch pin, the proximal latch and proximal latch pin being configured to engage with each other to lock the first and second handle portions (102, 104) pivotally together at proximal ends thereof, portions (102, 104) comprising a proximal latch and the other of the first and second handle portions (102, 104) comprising a proximal latch pin, the proximal latch and proximal latch pin being configured to engage with each other to lock the first and second handle portions (102, 104) pivotally together at proximal ends thereof, wherein the second handle portion further comprises a latch projection, and the first handle portion further comprises a clamp arm, the surgical instrument being characterized in that the first handle portion further comprises an over center linkage pivotally connected to the clamp arm at a first end and slidably connected to the first handle portion at a second end, the latch projection and over center linkage being configured to engage each other when the clamp arm is depressed to lock the surgical instrument in a closed position in which the handle portions (102, 104) are clamped together in proximity to each other; portion further comprises a latch projection, and the first handle portion further comprises a clamp arm, the surgical instrument being characterized in that the first handle portion further comprises an over center linkage pivotally connected to the clamp arm at a first end and slidably connected to the first handle portion at a second end, the latch projection and over center linkage being configured to engage each other when the clamp arm is depressed to lock the surgical instrument in a closed position in which the handle portions (102, 104) are clamped together in proximity to each other; wherein depression of the clamp arm causes the second end of the over center linkage to slide relative to the first handle portion from an unengaged position of the over center linkage to an engaged position in which the over center linkage engages the latch projection, wherein the first handle portion further comprises a clamp arm release slidable between engaged and unengaged positions and biased towards its engaged position, wherein the clamp arm release is retained in its unengaged position when the over center linkage is in its unengaged position and wherein the clamp arm release is permitted to move to its engaged position once the clamp arm has been moved to its depressed position, and position when the over center linkage is in its unengaged position and wherein the clamp arm release is permitted to move to its engaged position once the clamp arm has been moved to its depressed position, and wherein the clamp arm release is configured to retain the over center linkage in its engaged position and the clamp arm in its depressed position when the clamp arm release is in its engaged position and to permit the over center linkage to move to its unengaged position and the clamp arm to its undepressed position once the clamp arm release has been returned to its unengaged position.