Commitment letters setting out terms of loan agreements between the claimant and the 1st defendant – 3rd defendant’s guarantee agreement with the claimant – Whether summary judgment should be awarded to the claimant – Whether the 3rd defendant’s defence is one which has a realistic prospect of success – Variation of initial loan agreement – Circumstances in which guarantor will be discharged from guarantee agreement – Whether guarantee agreement was a continuing security – Whether guarantee agreement is applicable as between the claimant and the 3rd defendant