I don't know what source Jan Horn used for this but simple human error is always a possibile explanation for a discrepenancy. The designation Kommando Sperling was cancelled on 7 February, so officially there was only 1.(F)/123. Even so, on some days the British did intercept two reports giving the same return at slightly different times.
I don't have a strength return for 16 February but I have published
many others here and the unit never had eight serviceable aircraft that month.
The reported figures for 15 February were:
CX/MSS/R.464(C)
2. Serviceability return stamped 1630/15/2:
1. ((Total pilots)) }
2. ((Op.)) } 6
3. ((Ready)) }
4. ((Non-op.)) 0
5. ((Total a/c)) 8
6. ((Serviceability)) GH, HH, EH, BH serviceable
AH, IH, CH, FH, u/s.
Owing weather no ops.
NOTE: Source believes above from 1.(F)/123.
And for 21 February:
CX/MSS/R. 469 (C)
9. … ((2)) Dated 21/2:
Strength return:
1) ((Total pilots)) }
2) ((Op.)) } 13
3) ((Ready)) 12
4) ((Non. op.)) 0
5) ((Total a/c)) 6
6)) ((Serviceability)) 3 BH, CH, IH serviceable
AH, EH, FH unserviceable
NOTE:… Seen in file marked GAF Command WEST.
Source: ULTRA decrypts.