Question: What is the coverage whose local authority area under the MK postcode area became a self-governing unitary authority on 1 April 1997 ?

text: MK postcode area
Coverage
The approximate coverage of the postcode districts :
The MK postcode area, also known as the Milton Keynes postcode area, is a group of 26 postcode districts in England, within five post towns. These cover north Buckinghamshire (including Milton Keynes, Buckingham, Newport Pagnell and Olney), west and north Bedfordshire (including Bedford) and very small parts of Northamptonshire, Oxfordshire and Cambridgeshire.
Postcode district Post town Coverage Local authority area
MK1 MILTON KEYNES Denbigh , Mount Farm Milton Keynes
MK2 MILTON KEYNES Brickfields , Central Bletchley , Fenny Stratford , Water Eaton Milton Keynes
MK3 MILTON KEYNES Church Green , Far Bletchley , Old Bletchley , Newton Leys , West Bletchley Milton Keynes , Aylesbury Vale
MK4 MILTON KEYNES Emerson Valley , Furzton , Kingsmead , Oxley Park , Shenley Brook End , Snelshall West , Tattenhoe , Tattenhoe Park , Westcroft , Whaddon , Woodhill Milton Keynes , Aylesbury Vale
MK5 MILTON KEYNES Crownhill , Elfield Park , Grange Farm , Oakhill , Knowlhill , Loughton , Medbourne , Shenley Brook End , Shenley Church End , Shenley Lodge , Shenley Wood Milton Keynes
MK6 MILTON KEYNES Ashland , Beanhill , Bleak Hall , Coffee Hall , Eaglestone , Fishermead , Leadenhall , Netherfield , Oldbrook , Peartree Bridge , Redmoor , Springfield , Tinkers Bridge , Woughton on the Green , Woughton Park , Simpson , Winterhill Milton Keynes
MK7 MILTON KEYNES Browns Wood , Caldecotte , Kents Hill , Tilbrook , Walton , Walton Hall , Wavendon , Wavendon Gate , Old Farm Park Milton Keynes
MK8 MILTON KEYNES Crownhill , Grange Farm , Great Holm , Hazeley , Loughton , Loughton Lodge , Two Mile Ash , Whitehouse , Wymbush Milton Keynes
MK9 MILTON KEYNES Central Milton Keynes , Campbell Park Milton Keynes
MK10 MILTON KEYNES Brinklow , Broughton , Kingston , Middleton , Monkston , Oakgrove Milton Keynes
MK11 MILTON KEYNES Fairfields , Fullers Slade , Galley Hill , Kiln Farm , Stony Stratford Milton Keynes
MK12 MILTON KEYNES Greenleys , Hodge Lea , Old Wolverton , Stacey Bushes , Wolverton , Wolverton Mill Milton Keynes
MK13 MILTON KEYNES Bancroft/Bancroft Park , Blue Bridge , Bradwell and Bradwell Abbey , Bradwell Common , New Bradwell , Heelands , Stonebridge Milton Keynes
MK14 MILTON KEYNES Blakelands , Conniburrow , Downs Barn , Giffard Park , Great Linford , Linford Wood , Oakridge Park , Stantonbury , Neath Hill , Redhouse Park Milton Keynes
MK15 MILTON KEYNES Bolbeck Park , Downhead Park , Fox Milne , Newlands , Pennyland , Pineham , Northfield , Tongwell , Willen Park , Willen , Willen Lake , Great Woolstone , Little Woolstone Milton Keynes
MK16 NEWPORT PAGNELL Astwood , Broughton , Chicheley , Filgrave , Gayhurst , Hardmead , Lathbury , Little Crawley , Moulsoe , North Crawley , Newport Pagnell , Sherington , Stoke Goldington , Tyringham Milton Keynes
MK17 MILTON KEYNES Aspley Guise , Battlesden , Bow Brickhill , Drayton Parslow , Eversholt , Great Brickhill , Great Horwood , Hulcote , Little Brickhill , Little Horwood , Milton Bryan , Mursley , Nash , Newton Longville , Potsgrove , Salford , Stoke Hammond , Swanbourne , Thornton , Tingrith , Wavendon , Whaddon , Woburn , Woburn Sands Aylesbury Vale , Central Bedfordshire , Milton Keynes
MK18 BUCKINGHAM Addington , Adstock , Akeley , Barton Hartshorn , Botolph Claydon , Buckingham , Calvert , Chackmore , Chetwode , Dadford , Dunton , East Claydon , Finmere , Foscott , Gawcott , Granborough , Hillesden , Hoggeston , Leckhamstead , Lillingstone Dayrell , Lillingstone Lovell , Maids Moreton , Middle Claydon , Newton Purcell , North Marston , Padbury , Shalstone , Steeple Claydon , Tingewick , Thornborough , Water Stratford , Winslow Aylesbury Vale , Cherwell
MK19 MILTON KEYNES Beachampton , Calverton , Castlethorpe Cosgrove , Deanshanger , Hanslope , Haversham , Little Linford , Long Street , Old Stratford , Passenham , Upper Weald , Wicken Aylesbury Vale , Milton Keynes , South Northamptonshire
MK40 BEDFORD Biddenham , Castle , De Parys , Great Denham , Harpur , Queens Park Bedford