The FTSE 100 experienced a minor decline on Monday, as investors adopted a cautious stance in anticipation of Iran's response to the recent US airstrikes over the weekend. Leading oil companies, BP and Shell, saw earlier gains diminish as crude oil prices fell, due to reduced fears of supply disruptions in the Strait of Hormuz. The travel sector faced challenges, with shares of easyJet dropping over 2% and IAG falling almost 1.5%, as concerns mounted regarding potential travel disruptions. In contrast, National Grid, Fresnillo, Convatec Group, and Bunzl all saw their shares rise by more than 2%. Economic data provided a slight reprieve; the S&P Global's UK flash composite PMI for June increased to 50.7, slightly exceeding expectations and indicating modest growth in the private sector. The manufacturing sector contracted at a decreased rate, with a reading of 47.7, while the services sector met forecasts at 51.3. All metrics showed improvement from May, suggesting some resilience in the UK economy despite ongoing global tensions.