Retail giant Wesfarmers could abort its troubled invasion of the British Isles as soon as June after admitting it made serious mistakes when trying to transplant the successful Bunnings model to the northern hemisphere, according to a report in the Sydney Morning Herald.

Unveiling a $1 billion writedown of Bunnings UK and Ireland (BUKI) on Monday, Wesfarmers managing director Rob Scott said he would not let the troubled business hang over Wesfarmers for "years and years and years" in the way rival Woolworths was haunted by its disastrous Masters Home Improvement experiment.

"We need to provide some certainty and clarity," Mr Scott said as he announced a review into BUKI's future due back in June and revealed its first half losses would blow out to about $165 million.

That writedown is greater than the $705 million Wesfarmers paid for the home improvement chain Homebase in 2016, which it planned to convert to the Bunnings brand and format.

The news sent Wesfarmers’ plunging 4.5 per to close at $42.34 - the biggest one day fall since October 2016, and the second biggest one-day drop in eight and a half years.

“I appreciate what we’ve disclosed today is terrible news, terrible news for shareholders," Mr Scott was reported as saying the Sydney Morning Herald.

He said that "all options" - including an exit - were on the table. However an exit was not the preferred option and it would have been premature to make that decision before the review.

"To shut the door on this today would be incredibly damaging to shareholders, particularly where the current level of losses are," Mr Scott said.

 “This business was profitable two years ago, so we know that there is the capacity within this network when things are working to generate profitability."

In the meantime BUKI would try to improve sales at the remaining 231 Homebase stores.

Sales have suffered as Wesfarmers management alienated customers by removing important product categories and concession stores, and moving some to the Bunnings format.

Mr Scott said Wesfarmers had earmarked between 20 and 40 of the worst performing Homebase stores for possible closure.

The first 19 "pilot" Bunnings stores had seen some encouraging results, Wesfarmers said, but sales had suffered during the winter months when it did not have the right products. It was still searching for a "proof of concept" for the Bunnings format.

Five more Homebase stores are currently being turned into Bunnings, but Wesfarmers will not start any more conversions until the review is completed in June.

The full Sydney Herald report can be viewed at http://www.smh.com.au/business/retail/bunnings-uk-woes-deepen-with-1-billion-writedown-20180204-p4yze8.html