Having done a bit of digging around in the Pay Warrant 1899, courtesy of the Internet Archive, I have found a reference in Article 1176, to the payment of gratuities to soldiers on discharge for disability not caused by the service. Unfortunately the scanning has chopped off some of the left hand side of the page but it is still possible to make out the wording which reads as follows:
“Gratuity
In special cases, where it may be considered more advantageous to the soldier that a gratuity in money, proportional to the length of his service and the duration of the pension awarded, should be given instead of the temporary pension, a sum not exceeding £30 may be allowed”
Given that the civilian old age pension, set by the 1909 Old Age Pension Act, was 5s a week, I cannot believe that Pte Clarke was awarded a military pension of £7 10s per week for 72 days service in the Regular Army. It must have been a one-off payment, and quite a generous one considering the reason for his discharge was not attributable to his service.