Hi Kahu1
You're right! It's a British 1000lb HE Mark 6, 6*, 9, 11, 11* or 12 from the 1950s (i.e. the Canberra era). It's not possible to determine which Mark the bomb is just from looking at it. In summary, the Mk 6 had a forged body and was supplied with an Exploder and Detonator pocket in the tail position only; the Mk 6* was the same as the Mk 6 except it had a metallic sprayed coating on the body; the Mk 9 was the same as the Mk 6 except it had a cast steel body. The Mks 11, 11* and 12 were respectively the same as the Mks 6, 6* and 9, except that they were supplied with exploders and Detonator pockets in the nose and tail positions.
I hope this helps
eodda (aka Dave)