The wife of Henry Engelhardt, the Chief Executive Officer of car insurance group Admiral, topped up the family stake in the car insurance group again on Thursday, taking her investment in this week alone to over two million pounds.Diane Briere de l'Isle bought 45,500 shares at yesterday at a price of 1,108p, costing her £504,140. In addition to the other two shares purchase she made on Tuesday and Wednesday, she bought a total of 191,907 shares this week, spending a combined £2.12m.'Henry Engelhardt and Family' holdings now total 38,005,472 ordinary shares in Admiral, lifting its stake to over 14%.The purchases came just a few days after Admiral's first-half results (on August 30th) in which it reported a 7% rise in pre-tax profit to £171.8m and a 6% increase in group turnover to £1.17bn. However, the share price has been under pressure since the figures were released, falling by over 4%.Speaking at the time of the results, Engelhardt said: "In the UK, following the very significant growth in 2010 and 2011, we continue to slow our rate of growth to a more modest level, which we believe is a sensible response to the increased competition in the market." In other news, Marshall Evans, the Group Operations Director at AIM-listed blue-collar recruitment firm Staffline, entered into a transaction for the sale of 1,090,400 ordinary shares in the company yesterday in response to institutional demand.The shares, sold at a price of 217p a piece, generated around £2.37m for the executive after they were sold to institutional investors procured by Liberum Capital Limited, the company's nomad and broker.Top Director BuysAdmiral Group (ADM) Director name: Mr Henry EngelhardtAmount purchased: 45,500 @ 1,108.00p Value: £504,140Aseana Properties Ltd. (ASPL) Director name: Mr Gerald Ong Chong Keng Amount purchased: 500,000 @ $0.40 Value: $198,750Ironveld (IRON) Director name: Mr Charles Giles ClarkeAmount purchased: 2,500,000 @ 1.95p Value: £48,750Ironveld (IRON) Director name: Mr John Nicholas HarrisonAmount purchased: 2,000,000 @ 2.00p Value: £40,000Mcbride (MCB) Director name: Mr Chris BullAmount purchased: 20,000 @ 119.50p Value: £23,900Ironveld (IRON) Director name: Mr Charles Giles ClarkeAmount purchased: 1,000,000 @ 2.20p Value: £22,000May Gurney Integrated Services (MAYG) Director name: Baroness Margaret FordAmount purchased: 16,642 @ 119.50p Value: £19,887IPPlus (IPP) Director name: Mr William CatchpoleAmount purchased: 73,645 @ 15.00p Value: £11,047Top Director SellsStaffline Group (STAF) Director name: Mr Marshall EvansAmount sold: 1,090,400 @ 217.00p Value: £2,366,168Kingspan Group (KGP) Director name: Mr Russell ShielsAmount sold: 64,400 @ € 8.00 Value: € 515,200National Express Group (NEX) Director name: Mr Jez K MaidenAmount sold: 157,686 @ 214.53p Value: £338,284