Underperforming oil and mining stocks prevented the FTSE 100 from gaining positive momentum, causing it to close flat at 7,118.
Sterling remained strong against the dollar, acting as a further headwind against the index.
The blue-chip index bias towards overseas earnings saw it benefit from a weaker pound after the Brexit vote, but this trend reversed following UK Prime Minister Theresa May's shock decision to hold a snap general election in June.
Brent crude advanced 0.4% to $53 per barrel, while copper and gold prices were stable.
US equities bounced back from IBM's disappointing results as media reports suggested an extension of oil supply cuts led by the Organisation of Petroleum Exporting Countries (OPEC).
The S&P 500 opened 0.3% higher on Wednesday.
Asian markets didn't perform well as indices in Japan and China were flat on Thursday.
The only exception was the Hang Seng in Hong Kong, which closed 1% higher as investors felt less uneasy about geopolitical tensions with North Korea.
FTSE 100 RISERS AND FALLERS
Ben & Jerry's owner Unilever (ULVR) boosted its turnover in its first quarter of 2017 by 6.1% to €13.3bn, and hiked its quarterly dividend on a confident outlook.
Challenging weather conditions in Western Australia failed to bring Rio Tinto (RIO) down as the miner delivered solid production in the first quarter of 2017, but the stock was flat at £30.50.
More people tuned into NOW TV owner Sky (SKY) as recorded nine-month revenues jumped 11% in reported terms to £9.64bn thanks to growth in the UK, Ireland, Germany, Austria and Italy.
Overnight Ashtead's (AHT) peer United Rentals reported underwhelming earnings margins, which dragged the stock 2.7% lower to £15.79.
FTSE 250 RISERS AND FALLERS
Embattled Southern Rail operator Go-Ahead (GOG) maintained its full year expectations for its bus and rail divisions provided at its half year results in February. This was a relief for investors as the stock accelerated 3% to £17.82.
Packaging products supplier Essentra (ESNT) was 5.8% higher at 532.5p after announcing it was on a 'much more stable footing' entering 2017.
Investors were not thrilled with Debenhams (DEB) new CEO Sergio Bucher's plans to make the department stores a destination for 'social shopping'. Previously £350m was allocated to a turnaround plan out to 2020, but this cost was hiked by £100m.
Gold miner Acacia Mining (ACA) slumped 8.4% to 417.3p as it had no resolution for an export ban in its Tanzania base.
Asset manager Man Group (EMG) continued the upbeat trend in the sector as its assets under management rose 10% in its first quarter, prompting a 7% increase to 150.8p.
SMALL CAP RISERS AND FALLERS
Ortac Resources (OTC) agreed to form a joint venture with a Slovakian firm to jointly develop the Sturec Gold Project at Kremnica. It was seen as a golden deal as the stock soared 28% to 4p.
Middle East hotel owner Action Hotels (AHCG) struggled despite management expecting to report rises in full year total revenue and earnings on top of solid trading in its first quarter of 2017.