Possible Clues:

• Swamp primarily surrounding Irish lake
• A Berkshire town; marshy ground; to shed skin
• Swamp; shed (dead skin)
• Berkshire town, where, according to Betjeman, there 'isn't room to graze a cow' - but Wernham Hogg has an office
• Marshy place in Berkshire town
• Cast off
• The target for Betjeman's friendly bombs?
• Berkshire town and local authority
• Homonym for slew
• Cast off, beginning to sail on Irish lake