High street department store Marks & Spencer led retailers higher on Thursday morning, though the wider markets was kept broadly flat as concerns about Greece and UK political uncertainty limited upside.M&S shares surged 5.5% after an unexpected return to growth in clothing sales, while Dunelm and Booker also impressed with trading updates.The FTSE 100 was up just 0.04% at 6,812.14 in early deals.Markets will be closed on Friday and Monday and investors were showing signs of caution early on ahead of the long weekend.Thursday night will see the leaders of the seven top political parties in the UK battle it out in a live, televised debate in the run-up to the general election in May."As the election looms, and that seven-way mega-debate this evening, the FTSE's natural predilection for the next month may be stagnation, as investors try and wait out the increasingly uncertain election run-in," said Spreadex analyst Connor Campbell.Markets were also keeping an eye on Greece after Athens submitted a new proposal of economic reforms overnight "which is more specific and quantified", according to the Greek finance ministry. The 26-page document suggests that Greece could raise as much as €6bn this year as it looks to unlock €7.2bn in bailout funds before it runs out of money.Nevertheless, EU officials claimed that the new list still needs more work and a deal is not expected before the next meeting of Eurozone finance ministers on 24 April.Analysts at Barclays said the new list "represents a clear step in the right direction in our view" for Greece. "However, we do not think this document represents the last iteration of reform proposals exchanged by Athens and Brussels, given that it contains some elements that are likely to be further revised," they said.M&S shines in Q4In the fourth quarter Marks & Spencer delivered its first growth from clothing and general merchandise for 14 quarters, with like-for-like sales unexpectedly rising 0.7% in both clothing and food. The market had been expecting GM sales to fall and food to be flattish.UK homewares retailer Dunelm was also higher as it delivered a upbeat outlook after increasing sales by 10.7% in the third quarter, though growth did tail off slightly from the first half.Food wholesale retailer Booker rose after saying it had a "good end to a good year" with a 1% rise in fourth-quarter sales despite ongoing price deflation, as its chairman announced his resignation.Playtech's first move into the financial trading market was welcomed by investors as the online gaming group agreed to acquire forex and CFD provider company TradeFX, owner of the markets.com website, for up to €458m.Ingredient and beverage provider Tate & Lyle was higher after reiterating guidance for the current financial year, saying that it expected profit to be lower than initial estimates.A number of stocks went ex-dividend on Thursday, including DS Smith, Wolseley, Game Digital, IHG and Lloyds.Market MoverstechMARK 3,156.36 +0.40%FTSE 100 6,812.14 +0.04%FTSE 250 17,210.42 +0.51%FTSE 100 - RisersMarks & Spencer Group (MKS) 559.50p +5.47%Coca-Cola HBC AG (CDI) (CCH) 1,266.00p +3.60%Hikma Pharmaceuticals (HIK) 2,197.00p +3.10%Imperial Tobacco Group (IMT) 3,107.00p +2.04%Randgold Resources Ltd. (RRS) 4,851.00p +1.04%Weir Group (WEIR) 1,712.00p +1.00%Associated British Foods (ABF) 2,840.00p +0.85%ARM Holdings (ARM) 1,104.00p +0.82%Aggreko (AGK) 1,563.00p +0.77%London Stock Exchange Group (LSE) 2,465.00p +0.74%FTSE 100 - FallerseasyJet (EZJ) 1,841.00p -1.66%BHP Billiton (BLT) 1,446.50p -1.60%Hargreaves Lansdown (HL.) 1,145.00p -1.46%Kingfisher (KGF) 362.80p -1.41%Glencore (GLEN) 280.35p -1.32%Antofagasta (ANTO) 724.00p -1.30%International Consolidated Airlines Group SA (CDI) (IAG) 592.50p -1.25%InterContinental Hotels Group (IHG) 2,610.00p -1.21%Anglo American (AAL) 1,006.00p -1.03%TUI AG Reg Shs (DI) (TUI) 1,199.00p -0.99%FTSE 250 - RisersBTG (BTG) 776.50p +5.29%Playtech (PTEC) 808.00p +4.06%Centamin (DI) (CEY) 58.75p +3.80%Soco International (SIA) 160.00p +3.23%Rathbone Brothers (RAT) 2,110.00p +2.88%Telecom Plus (TEP) 914.00p +2.81%Cranswick (CWK) 1,400.00p +2.71%Premier Oil (PMO) 137.00p +2.54%Aveva Group (AVV) 1,484.00p +2.34%Renishaw (RSW) 2,486.00p +2.26%FTSE 250 - FallersLadbrokes (LAD) 101.20p -2.88%John Laing Infrastructure Fund Ltd (JLIF) 123.50p -2.60%Betfair Group (BET) 2,195.00p -2.05%Serco Group (SRP) 141.90p -1.87%Vedanta Resources (VED) 488.50p -1.47%JD Sports Fashion (JD.) 478.00p -1.44%Redrow (RDW) 355.10p -1.22%Worldwide Healthcare Trust (WWH) 1,868.00p -1.06%Smith (DS) (SMDS) 342.10p -1.01%Murray International Trust (MYI) 1,015.00p -0.98%