(ShareCast News) - Rio Tinto non-executive director Michael L'Estrange almost doubled his stake in the mining heavyweight with a AU$44,590 (£23,000) purchase on Wednesday.Professor L'Estrange, formerly Australia's high commissioner to the United Kingdom and ex secretary of the Department of Foreign Affairs and Trade, bought 1,000 shares at a price of 44.59 Australian dollars apiece, taking his stake to 2,003 shares.L'Estrange joined Rio's board in 2014, when the share price was above AUD60, it has recently been below AUD40 as the company and its peers have been slammed by crashing commodity prices.Rio late last month priced an offer to buy back $1.36bn in debt, as it looks to cut debt amid the commodity downturn, but earlier in May it said it was pressing on with the $5.3bn expansion of its Oyu Tolgoi copper and gold mine in Mongolia. Top Director BuysRio Tinto (RIO)Director name: L'Estrange ,MichaelAmount purchased: 1,000 @ A$44.59Value: A$23,419.12Wolf Minerals Limited (WLFE)Director name: Hopkins,John Amount purchased: 71,899 @ 9.00pValue: £6,470.91Wolf Minerals Limited (WLFE)Director name: Hopkins,John Amount purchased: 71,899 @ 9.00pValue: £6,470.91Wolf Minerals Limited (WLFE)Director name: Royston Clarke,Nicholas Amount purchased: 35,950 @ 9.00pValue: £3,235.50Wolf Minerals Limited (WLFE)Director name: Newport,DonAmount purchased: 35,950 @ 9.00pValue: £3,235.50Wolf Minerals Limited (WLFE)Director name: Hugh Beevor,RonaldAmount purchased: 35,950 @ 9.00pValue: £3,235.50Foreign And Colonial Inv Trust (FRCL)Director name: Bone,RogerAmount purchased: 228 @ 437.51pValue: £997.52Foreign And Colonial Inv Trust (FRCL)Director name: Hewitt,JeffreyAmount purchased: 114 @ 437.51pValue: £498.76Mondi (MNDI)Director name: King,AndrewAmount purchased: 11 @ 1,307.50pValue: £143.82Mondi (MNDI)Director name: Hathorn,David AAmount purchased: 11 @ 1,307.50pValue: £143.82Meggitt (MGGT)Director name: Young,Stephen GAmount purchased: 31 @ 410.00pValue: £127.10Meggitt (MGGT)Director name: Webb,DougAmount purchased: 31 @ 410.00pValue: £127.10Drs Data & Research Services (DRS)Director name: Tebbutt,Arthur MAmount purchased: 1,262 @ 9.90pValue: £124.94Meggitt (MGGT)Director name: Green,Philip ErnestAmount purchased: 30 @ 410.00pValue: £123.00Top Director SellsBt Group (BT.A)Director name: Patterson,GavinAmount purchased: 307,356 @ 445.00pValue: £1,367,734.14Bt Group (BT.A)Director name: Chanmugam,TonyAmount purchased: 145,508 @ 445.00pValue: £647,510.57Bt Group (BT.A)Director name: Chanmugam,TonyAmount purchased: 142,877 @ 445.00pValue: £635,802.62