I type a lot of letters, and I type that sentence a lot.
How about instead of relying on patients who may be vulnerable to remember to bring a list of their medication - which some may presume their consultant already has access to - the GP obtain consent from the patient before making the referral to the consultant to email a list of their medication along with the referral. Maybe IT folk could create a field that already populates that info into referral letters automatically and the GP can edit it out if they so desire.
Try using the summary care record (https://portal.national.ncrs.nhs.uk/portal/) on the NHS spine.
Have had this problem in our Pre-Op assessment service. Now all our nurses can log into this with their smart cards and can see the patient's medications.