Merge pull request #149 from alphagov/string-exp #327

Job	Run time
Test Ruby	14s
CodeQL SAST scan / Analyze	44s
Dependency Review scan / dependency-review-push	6s
Dependency Review scan / dependency-review-pr	0s
Lint Ruby / Run RuboCop	10s
Security Analysis / Run Brakeman	8s
	1m 22s

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