Petersford plc prepares accounts to 31 December each year. On 1 January 2014, the company acquired a non-current asset at a cost of £256,000 and decided to depreciate this asset on the straight-line basis over a five-year period, assuming a residual value of £nil. Depreciation allowed for tax purposes with regard to this asset in the first five years of ownership are as follows:
                                                                £
Year to 31 December 2014.......... 102,400
Year to 31 December 2015............ 38,400
Year to 31 December 2016............ 28,800
Year to 31 December 2017............ 21,600
Year to 31 December 2018............ 16,200

The company's pre-tax profit (after charging depreciation) was £500,000 in the year to 31 December 2014 and remained at a consistent £500,000 per annum for each of the next four years.

There are no other non-current assets and there are no differences between taxable profit and accounting profit other than those relating to depreciation. A tax rate of 20% applies throughout.

(a) Without making use of the "tax base" concept, show the necessary transfers to and from the deferred tax account for each of the five years to 31 December 2018. Also calculate and explain the closing balance on this account at 31 December 2018.

(b) Re-work this exercise using the tax base concept.