The energy giant stripped out the valuations from its preliminary accounts last week. Steve Lucas said calculating the effects put an unwanted burden on the finance function.

‘It’s a lot of work and there is no economic benefit. Whether shareholders find the information more useful [when fair value is taken into account] I really don’t know.’

The company took a hit of £16m as fair value bit into the worth of its derivatives contracts, but disclosed the change as an exceptional item.

National Grid made a point of flagging up the ‘complex nature of hedge accounting under IAS 39’ in its latest annual report, warning shareholders that some derivatives may not qualify for hedge accounting under the rules.

The company enters into derivative deals in order to manage its interest rate and foreign currency exposures. The main derivatives used include interest rate swaps, currency swaps and commodity contracts.

The fair values move with the strength of the capital markets, which can generate volatility in its numbers.

The energy giant reported a strong set of preliminary results as operating profit rose by up 29% to almost £2.6bn. Profit before tax went up by 24% and earnings per share rose by a quarter, but these numbers were presented independent of fair value changes.

National Grid said in its results: ‘This presentation is based on continuing business performance, so it excludes exceptional items and remeasurements.’

‘[The swings] that arise from changes in mark-to-market values or exchange rates and are reflected in the income statement to the extent that hedge accounting is not achieved, or is not fully effective,’ the company said.

The company is also listed in the US where it conducts half of its business and Lucas said convergence between IFRS and US GAAP could not come quick enough in terms of reporting demands.

‘At the moment, we’re juggling both requirements and talking in two languages and it’s not easy being bilingual.’