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- Magdalen Quarry
- Magnolia Fields (or Magnolia Park)
- Maiden Eriegh Lakes
- Maidscross Hill
- Maltby Commons
- Malvern & Brueton Park – Solihull, West Midlands
- Manor Road Community Woodland
- Marden Quarry
- Mardley Heath
- Mare Fen
- Mareham Pastures – Lincolnshire
- Marline Wood
- Marsden Old Quarry – South Tyneside
- Marshall's Arm – Cheshire West and Chester
- Marshalls Heath
- Marshes Hill Common – Staffordshire Moorlands
- Marston Marsh
- Marston Thrift
- Martins Pond – Nottingham
- Marton Mere – Blackpool
- Marton West Beck Valley – Cleveland
- Marylands
- Maryon Wilson Park & Gilbert's Pit
- Matford
- Matlock Parks – Debyshire Dales
- Maulden Church Meadows
- Maun Valley Park
- Mayfield Broom – Goole Parish/East Riding of Yorkshire
- Mayford Meadows
- Maysbrook Park, South
- Maze Park Nature Reserve
- McIlroy Park (Part of West Reading Woodlands)
- Meanwood Valley – Leeds
- Meddon Green Local Nature Reserve
- Melwood
- Mercury Marshes
- Merrion's Wood – Walsall
- Mersey Vale Nature Park - Stockport
- Merton Park Green Walks
- Middle Hill Common
- Middleton Woods – Leeds
- Mill Farm
- Mill Hill Old Railway
- Mill Lane, Walsall – Walsall
- Mill Meadows
- Mill Wood and Alder Wood – Liverpool
- Millennium Wood – Macclesfield
- Millfield Pond
- Millhams Mead
- Millington Wood – East Riding of Yorkshire
- Millisons Wood – Solihull, West Midlands
- Millom Ironworks – Cumbria
- Milner Royd
- Moira Junction – Leicestershire
- Moldrums Ground
- Mole Valley Corridor
- Molesey Heath
- Moorcroft Wood – Walsall
- Morden Park
- Moreton Hall Community Woods
- Morley Quarry – Charnwood, Leicestershire
- Moseley Bog – Birmingham
- Mousehold Heath
- Mousley Bottom – Derbyshire
- Mousesweet Brook – Sandwell, West Midlands
- Mowbray Fields
- Mowsbury Hill
- Mudchute Park Farm
- Murdishaw Wood & Valley – Halton, Cheshire
- Muxton Marsh – Telford and Wrekin
- Myrna Close
Read more about this topic: List Of Local Nature Reserves In England