The attestation clause is the bit at the bottom which reads "Signed as a testator by him in our presence and then by us in his presence". Basically, this recites s15 Wills Act 1837 which broadly states that a will should be signed by a testator in the presence of two or more witnesses who should then attest and sign the will in the presence of the testator. No form of attestation is necessary under s15, however, without it, the Probate Registrar will usually ask for an affidavit of due execution from one or both of the witnesses to swear the circumstances in which the will was executed. As long as the witness is able to confirm that s15 was complied with, there should be no further problem. What exactly does your attestation clause say?