diff --git a/lib/ndr_support/string/clean_methodable.rb b/lib/ndr_support/string/clean_methodable.rb
new file mode 100644
index 0000000..aff66ef
--- /dev/null
+++ b/lib/ndr_support/string/clean_methodable.rb
@@ -0,0 +1,140 @@
+# Adds the 'clean' method to String, which can be used to clean strings in various ways
+# depending on the contents
+module CleanMethodable
+  extend ActiveSupport::Concern
+
+  CLEAN_METHODS = {
+    nhsnumber: :clean_nhsnumber,
+    postcode: :clean_postcode, get_postcode: :clean_postcode,
+    lpi: :clean_lpi,
+    gender: :clean_gender, sex: :clean_sex, sex_c: :clean_sex_c,
+    name: :clean_name,
+    ethniccategory: :clean_ethniccategory,
+    code: :clean_code, code_icd: :clean_code_icd, icd: :clean_icd,
+    code_opcs: :clean_code_opcs,
+    hospitalnumber: :clean_hospitalnumber,
+    xmlsafe: :clean_xmlsafe, make_xml_safe: :clean_xmlsafe,
+    roman5: :clean_roman5,
+    tnmcategory: :clean_tnmcategory,
+    strip: :strip, upcase: :upcase, itself: :itself
+  }.freeze
+
+  def clean(what)
+    cleaning_method = CLEAN_METHODS[what]
+    return send(cleaning_method) if cleaning_method
+
+    gsub(' ?', ' ')
+  end
+
+  private
+
+  def clean_nhsnumber
+    delete('^0-9')[0..9]
+  end
+
+  def clean_postcode
+    postcodeize(:db)
+  end
+
+  def clean_lpi
+    upcase.delete('^0-9A-Z')
+  end
+
+  def clean_gender
+    return '1' if self =~ /\AM(ale)?/i
+    return '2' if self =~ /\AF(emale)?/i
+
+    self
+  end
+
+  def clean_sex
+    # SECURE: BNS 2012-10-09: But may behave oddly for multi-line input
+    return '1' if self =~ /^M|1/i
+    return '2' if self =~ /^F|2/i
+
+    '0'
+  end
+
+  def clean_sex_c
+    return 'M' if self =~ /^M|1/i
+    return 'F' if self =~ /^F|2/i
+
+    ''
+  end
+
+  def clean_name
+    substitutions = {
+      '.'      => '',
+      /,|;/    => ' ',
+      /\s{2,}/ => ' ',
+      '`'      => '\''
+    }
+    substitutions.inject(upcase) { |a, e| a.gsub(*e) }.strip
+  end
+
+  def clean_ethniccategory
+    replace_ethniccategory = {
+      '0' => '0', '1' => 'M', '2' => 'N',
+      '3' => 'H', '4' => 'J', '5' => 'K',
+      '6' => 'R', '7' => '8', '&' => 'X',
+      ' ' => 'X', '99' => 'X'
+    }
+    replace_ethniccategory[self] || upcase
+  end
+
+  def clean_code
+    split_on_separators.map do |code|
+      code.blank? ? next : code.delete('.')
+    end.compact.join(' ')
+  end
+
+  def clean_code_icd
+    warn '[DEPRECATION] clean(:code_icd) is deprecated - consider using clean(:icd) instead.'
+    # regexp = /[A-Z][0-9]{2}(\.(X|[0-9]{1,2})|[0-9]?)( *(D|A)( |,|;|$))/
+    codes = upcase.split_on_separators.delete_if { |x| x.squash.blank? }
+    cleaned_codes = []
+    codes.each do |code|
+      if code == 'D' || code == 'A'
+        cleaned_codes[-1] += code
+      else
+        cleaned_codes << code
+      end
+    end
+    cleaned_codes.join(' ')
+  end
+
+  def clean_icd
+    codes = upcase.squish.split_on_separators.reject(&:blank?)
+    codes.map { |code| code.gsub(/(?<=\d)(\.?X?)/, '') }.join(' ')
+  end
+
+  def clean_hospitalnumber
+    self[-1..-1] =~ /\d/ ? self : self[0..-2]
+  end
+
+  def clean_xmlsafe
+    strip_xml_unsafe_characters
+  end
+
+  def clean_roman5
+    # This deromanises roman numerals between 1 and 5
+    gsub(/[IV]+/i) { |match| ROMAN_ONE_TO_FIVE_MAPPING[match.upcase] }
+  end
+
+  def clean_tnmcategory
+    sub!(/\A[tnm]/i, '')
+    if self =~ /\Ax\z/i
+      upcase
+    else
+      downcase
+    end
+  end
+
+  def clean_code_opcs
+    split_on_separators.map do |code|
+      db_code = code.squash
+      next unless 4 == db_code.length || db_code =~ /CZ00[12]/
+      db_code
+    end.compact.join(' ')
+  end
+end
diff --git a/lib/ndr_support/string/cleaning.rb b/lib/ndr_support/string/cleaning.rb
index a3773fc..7681c92 100644
--- a/lib/ndr_support/string/cleaning.rb
+++ b/lib/ndr_support/string/cleaning.rb
@@ -1,6 +1,11 @@
 require 'active_support/core_ext/string/filters'
+require 'ndr_support/string/clean_methodable'
 
+# Extends String clean with various methods of cleaning strings
+# zand polishing them
 class String
+  include CleanMethodable
+
   INVALID_CONTROL_CHARS = /[\x00-\x08\x0b-\x0c\x0e-\x1f]/
   ROMAN_ONE_TO_FIVE_MAPPING = { 'I' => '1', 'II' => '2', 'III' => '3', 'IIII' => '4', 'IV' => '4', 'V' => '5' }
 
@@ -26,9 +31,8 @@ def squash
   # Parameter "option" can be :user, :compact, :db
   def postcodeize(option = :user)
     nspce = gsub(/[[:space:]]/, '').upcase
-    unless nspce.blank? || POSTCODE_REGEXP =~ nspce
-      return self # Don't change old-style or malformed postcodes
-    end
+    return self unless nspce.blank? || POSTCODE_REGEXP =~ nspce # Don't change old-style or malformed postcodes
+
     case option
     when :compact
       nspce
@@ -43,106 +47,6 @@ def postcodeize(option = :user)
     end
   end
 
-  def clean(what)
-    case what
-    when :nhsnumber
-      delete('^0-9')[0..9]
-    when :postcode, :get_postcode
-      postcodeize(:db)
-    when :lpi
-      upcase.delete('^0-9A-Z')
-    when :gender
-      if self =~ /\AM(ale)?/i
-        '1'
-      elsif self =~ /\AF(emale)?/i
-        '2'
-      else
-        self
-      end
-    when :sex
-      # SECURE: BNS 2012-10-09: But may behave oddly for multi-line input
-      if self =~ /^M|1/i
-        '1'
-      elsif self =~ /^F|2/i
-        '2'
-      else
-        '0'
-      end
-    when :sex_c
-      if self =~ /^M|1/i
-        'M'
-      elsif self =~ /^F|2/i
-        'F'
-      else
-        ''
-      end
-    when :name
-      substitutions = {
-        '.'      => '',
-        /,|;/    => ' ',
-        /\s{2,}/ => ' ',
-        '`'      => '\''
-      }
-      substitutions.inject(upcase) { |a, e| a.gsub(*e) }.strip
-    when :ethniccategory
-      replace_ethniccategory = {
-        '0' => '0',
-        '1' => 'M',
-        '2' => 'N',
-        '3' => 'H',
-        '4' => 'J',
-        '5' => 'K',
-        '6' => 'R',
-        '7' => '8',
-        '&' => 'X',
-        ' ' => 'X',
-        '99' => 'X'
-      }
-      replace_ethniccategory[self] || upcase
-    when :code
-      split_on_separators.map do |code|
-        code.blank? ? next : code.delete('.')
-      end.compact.join(' ')
-    when :code_icd
-      warn '[DEPRECATION] clean(:code_icd) is deprecated - consider using clean(:icd) instead.'
-      # regexp = /[A-Z][0-9]{2}(\.(X|[0-9]{1,2})|[0-9]?)( *(D|A)( |,|;|$))/
-      codes = upcase.split_on_separators.delete_if { |x| x.squash.blank? }
-      cleaned_codes = []
-      codes.each do |code|
-        if code == 'D' || code == 'A'
-          cleaned_codes[-1] += code
-        else
-          cleaned_codes << code
-        end
-      end
-      cleaned_codes.join(' ')
-    when :icd
-      codes = upcase.squish.split_on_separators.reject(&:blank?)
-      codes.map { |code| code.gsub(/(?<=\d)(\.?X?)/, '') }.join(' ')
-    when :code_opcs
-      clean_code_opcs
-    when :hospitalnumber
-      self[-1..-1] =~ /\d/ ? self : self[0..-2]
-    when :xmlsafe, :make_xml_safe
-      strip_xml_unsafe_characters
-    when :roman5
-      # This deromanises roman numerals between 1 and 5
-      gsub(/[IV]+/i) { |match| ROMAN_ONE_TO_FIVE_MAPPING[match.upcase] }
-    when :tnmcategory
-      sub!(/\A[tnm]/i, '')
-      if self =~ /\Ax\z/i
-        upcase
-      else
-        downcase
-      end
-    when :strip, :upcase, :itself
-      # SECURE: 14-06-2017 TPG Fixed list of executable methods (whats)
-      send(what)
-    else
-      gsub(' ?', ' ')
-    end
-  end
-
   def strip_xml_unsafe_characters
     gsub(String::INVALID_CONTROL_CHARS, '')
   end
@@ -156,14 +60,4 @@ def xml_unsafe?
   def split_on_separators(regexp = / |,|;/)
     split(regexp)
   end
-
-  private
-
-  def clean_code_opcs
-    split_on_separators.map do |code|
-      db_code = code.squash
-      next unless 4 == db_code.length || db_code =~ /CZ00[12]/
-      db_code
-    end.compact.join(' ')
-  end
 end