My only criticism, and it is very minor, is that there are three “reverse” clues in a row among the down clues.
ACROSS
1 EST-H-ETE – I can’t explain the H in this clue – EST and ETE are French words for “east” and summer (“season”), and ESTHETE is an American spelling of “aesthete”
6 SCAPI – A featured in (pics)* – flower stalks (singular – scape)
10 ON ACCOUNT
11 BARGE-COUPLE – UP in (gable core)* – Chambers only has this in the plural, meaning gable rafters
14 I-DAN-T
16 (<=NOD-ALEC) – Chinese pale green pottery
18 EN-1 AC. – Electrinic Numerical Integrator and Computer, a massice supercomputer built in the 50s
20 OUTDATE – reverse cryptic – “tead” = out (i.e. – anagram of) “date”
25 OUTSIZED
26 SU’S-CITATION
27 OL(FACT)IVE
28 NY(A)LA – NY = New York and La = Louisiana – a NYALA is a large South African antelope
29 A(CID-D)YE
DOWN
1 EMBL(emat)IC – an East Indian tree
2 S(LAND)ER(i)OUSLY
3 TERVALENT – VALE in (Trent)*
4 HOGAN – a log hut or a Dutch word for strong liquor
5 TACK-(<=MOOR)
7 COP-LAND
8 PNEUMATOLOGY – homophone of NEW, MAT + OLOGY
13 FRIAR-(<=DRIB) – an Australian honeyeater
15 (<=CITE-RUNE)
17 (<=LASS-Y-B.A.)
19 (<=NO MO-NG) – the GNOMON is the upright bit on a sundial that casts the necessary shadow
22 TIC(o)-CA – means “hired”, a Tico being a native or inhabitant of Costa Rica
On the other hand, the British, having build a large electronic computer Colossus at Bletchely Park, and who were arguably ahead of the americans, destroyed everything and kept it all secret until the 1970s. The faceless civil servant who took that decision probably put back computer science in Britain by decades and certainly the Americans from that point on were always ahead.
Paul
In an old Chambers, I found this definition –
Esth – an Estonian of the original Finnish stock