London's top stocks have made a cautious start as investors reflect on more huge losses at British Airways and Royal Bank of Scotland. Later today the keenly watched US monthly non-farm payroll figures also come out. British Airways reported a record loss of £292m and urged Unite to withdraw its plans for a strike ballot and resume talks with the carrier. The loss before tax of £292m, or £244m before restructuring costs, compares with a profit of £52m last year. Revenue was down 13.7% to £4.1bn. Net losses came to £208m.More huge write-offs sent Royal Bank of Scotland deep into loss over the past three months. The state-controlled bank that on Tuesday announced another £33bn cash injection from the government lost £2.1bn in the three months to September compared to a profit of £1.9bn. Nine-month losses now total £2.06bn against a profit £1.8bn this time last year.Pest controller Rentokil Initial more than doubled profit at actual exchange rates during the third quarter as losses at its parcels arm City Link narrowed substantially.Interim profits slumped at Tate & Lyle, with the sugar and sweeteners group cautioning that US markets remain under pressure. Sales in the half year to September increased by 7% to £1.82bn. Adjusted operating profit reduced by 1% (16% in constant currency) to £148m, with underlying profit before tax down by 13% (25% in constant currency) to £112m.Smith & Nephew's pre-tax profit jumped 45% in the third quarter and the knee and hip joint supplier expects a good outcome for the full year. Pre-tax profit for the three months to 26 September grew to $173m from $119m a year ago, lifting it to $495m for the nine months from $402m in 2008.A pick up in corporate businesses in the UK helped stockbroker Collins Stewart swing back into profit over the last four months. Total revenues in the period to end October rose by 4% to £57m with overall revenues for businesses based outside the US significantly ahead of the same period in 2008.