The question is split into Part A (contract law) and Part B (tort law), you must answer BOTH parts. A maximum of half of the words can be used in Part A and half of the words in Part B.
Part One  – Contract Law
George Zirkos inherits a large area of land and buildings in rural Essex from his grandmother and decides that, rather than live in the property, he will turn it into luxury flats and rent them out as holiday apartments. George employs a building firm, Johnson and Co, to do the work of redeveloping the property so that it will be suitable for the rental market. On 1 January 2018, Johnson and Co enter into an agreement with George to do the work with completion due by 31 December 2018. The agreement provides that failure to complete the work by that date will trigger a penalty clause, meaning that Johnson and Co will lose 1% of the contract price for every week that they are late in completing the redevelopment.
On 1 April 2018, Johnson and Co enter into another contract with subcontractor Preston Plumbers to complete the plumbing and heating work within the buildings for £150,000, with completion due by 30 October 2018. By 1 August, it becomes clear to Preston Plumbers that it cannot complete the work on time because i) it has underestimated the work involved in the job, ii) a higher than expected number of its staff have been off sick, and iii) it is struggling to get building supplies because of a recent global shortage.  Preston Plumbers approaches Johnson and Co to let them know that they are going to struggle to complete the job on time. James Johnson, Managing Director of Johnson and Co, offers to pay an extra £15,000 out of his own funds on the condition that the work is completed no later than 30 October as originally agreed. Preston Plumbers complete the job on time. Is the promise to pay an additional £15,000 enforceable?
Part Two – Tort Law
‘[T]he question of what amounts to “such care as in all the circumstances of the case is reasonable” depends upon assessing … not only the likelihood that someone may be injured and the seriousness of the injury which may occur, but also the social value of the activity which gives rise to the risk and the cost of preventative measures. These factors have to be balanced against each other.’  Lord Hoffmann, para 34 in Tomlinson v Congleton Borough Council [2004] 1 AC 46.
Critically analyse the above statement about the way in which the courts assess the standard of care in a negligence claim.