UBS upgrades oil and gas firm BG Group to a 'buy', from 'neutral', following the group's recent share price weakness since its disappointing first quarter results.Share are 7% lower since the its first quarter figures were announced last week, and are 15% off highs in April as oil prices have consolidated, the broker notes."We regard BG as a high quality long-term growth story, the shares of which are usually fully valued. However, buying on dips has proved a fruitful strategy and we currently see an opportunity," UBS said.Meanwhile, the target price is unchanged at 1,550p.Peel Hunt says that Land Securities' full-year figures were significantly better and expects more to come, saying that there appears to be little "drag factors" in the results."[Land Securities has the] Best niche exposures amongst leaders - thus our core recommendation (London 61%, retail parks 12.3%). There appears to be little 'drag' factors in the results with all major categories of property showing material gains in H2 [second half]."A 'buy' is retained, while the target price is increased from 781p to 790p.Nomura has upped its target price by 5% for tobacco titan British American Tobacco, saying that the company has a commitment to margin progression, good pricing visibility, and improving volume trends.The broker said the group's investor event saw senior management present a "self-assured outlook" on industry trends, and express its confidence on margins of over 35% this year (a year earlier than target) and around 40% by 2014/15.The target price now stands at 2,950p, from 2,800p, while a 'buy' rating is kept.