(ShareCast News) - London's FTSE 250 fell slightly on Thursday, down 0.25% to 17,731.01 at 1456 BST.Tullow Oil led the fallers, declining 8.67% to 222.20p while fellow oil company Premier Oil was not far behind, falling by 7.81% to 116.80p. The pair suffered at the hands of falling oil prices as a supply shortage spooked the market.Lonmin's plunge continued as its share price fell, by 7.88% to 40.91p. The miner has lost more than 80% in the last 12 months and continued to struggle to amidst falling platinum prices.Aggreko also fell as the company warned of a tough year ahead and it continued to work through restructuring to combat a weak oil and gas market. Shares in the company fell by 3.71% to 1,143p after it noted increased competition and geopolitical uncertainty.Going the other way Cobham led the risers, despite pre-tax profits taking a knock. The manufacturer's profits were cut due the costs of acquiring rival Aeroflex, but it noted revenue was up by about a quarter.Enterprise Inns rose by more than 4% to 278.20p after the company said like for like net income was up 0.5% higher. The result surprised analysts which had expected flatter figures.Phoenix Group Holdings rose after analysts said its 'A' rating from Fitch would put the insurer in a much better position to do mergers and acquisition in the UK. JP Morgan said the rating from Fitch was a positive development and reiterated an 'overweight' position on the stock. FTSE 250 - Risers Cobham (COB) 278.20p +5.98% Enterprise Inns (ETI) 119.30p +4.01% Phoenix Group Holdings (DI) (PHNX) 896.00p +2.99% Bovis Homes Group (BVS) 1,180.00p +2.43% Ted Baker (TED) 3,274.00p +2.38% UDG Healthcare Public Limited Company (UDG) 527.50p +2.23% Aldermore Group (ALD) 264.00p +2.21% Supergroup (SGP) 1,476.00p +1.93% Berkeley Group Holdings (The) (BKG) 3,453.00p +1.83% Dairy Crest Group (DCG) 599.50p +1.78% FTSE 250 - Fallers Tullow Oil (TLW) 222.20p -8.67% Lonmin (LMI) 40.91p -7.88% Premier Oil (PMO) 116.80p -7.81% Ophir Energy (OPHR) 108.30p -5.66% Just Eat (JE.) 398.90p -3.88% Aggreko (AGK) 1,143.00p -3.71% IP Group (IPO) 205.80p -3.06% Vedanta Resources (VED) 399.20p -2.97% Pace (PIC) 358.10p -2.95% RPC Group (RPC) 652.50p -2.54%