Alex,
Because you have not contacted the publisher of the magazine "Suomen Ilmailuhistoriallinen Lehti", he (Pentti Manninen) has compiled for you the main points of the topic, which have been discussed in several issues of the magazine. He is not a member of this forum and that's why I am forwarding the document below.
Matti
RAF serials with FinnAF Bristol Blenheim I & IV
Finnish Bristol Blenheim I (1st batch) construction numbers (extract from SIL issue 2/2019 page 2).
As the supplier in the case of the first 18 Blenheim airframes was directly manufacturer no RAF identities are naturally available. The original Bristol c/n followed tightly as planned the FinnAF BL-serial but not in all cases. Identities of BL-106 and BL-107 were swapped in a emergency in Filton due incorrect ferry crew name lists per aircraft distributed via diplomatic channels to overflown countries (Holland, Germany, Denmark and Sweden). It was easier to rename BL-106 as BL-107 and so avoid bureaucratic and diplomatic message problems.
The BL-119 was also an exception. It was held back in purpose and not accepted in its turn. BL-119 marked Blenheim was in the reality the last airframe BL-121 (c/n 8154) which was intended to be fitted with float undercarriage by Shorts Brothers. This airframe was to be left behind to wait for reworking by Shorts. This project however fell through and c/n 8154 was accepted as the last of the lot and got painted as BL-119.
c/n / FinnAF
8137 BL-104
8138 BL-105
8140 BL-106
8139 BL-107
8141 BL-108
8142 BL-109
8143 BL-110
8144 BL-111
8145 BL-112
8146 BL-113
8147 BL-114
8148 BL-115
8149 BL-116
8150 BL-117
8151 BL-118
8154 BL-119
8153 BL-120
8152 BL-121
For the assistance in this project our sincere thanks to Duncan Greenman and AIRchive.
Bristol Blenheim I - Winter War aid by Great Britain (extract from SIL issue 1/2016 page 2).
No.41 (Maintenance) Group HQ received 19 January 1940 instructions from Air Ministry to select and prepare 12 Blenheim I bombers complete with operational equipment for resale to the Bristol Co. for Finland. All of this lot were well used RAF aircraft, mainly used previously by RAF 21, 104 and 108 Squadrons and some training units. All RAF markings were replaced with Finnish equivalent ones. But at least BL-143 carried the 108 Sqn emblem on fin - still in June 1941.
RAF supplied Blenheim Ís to FinnAF during Winter War:
L1184 / BL-134
L1354 / BL-135
L1345 / BL-136
L1362 / BL-137
L1175 / BL-138
L1220 / BL-139
L1217 / BL-140
L1193 / BL-141
L1189 / BL-142
L1215 / BL-143
L1221 / BL-144
L1347 / BL-145
This short but extensively researched topic was made possible by the generous help from Phil Butler and Sqn Ldr Andrew Thomas. ID secured from A.M.Form 78 cards and corresponding FinnAF aircraft & engine files.
Bristol Blenheim and Modification 732 (extract from SIL issue 1/2015 page 2).
The Bristol Blenheim light bomber was developed without normal prototype and development work. The production was started prematurely and this meant constant flow of technical modifications supplied by Bristol Aircraft Co.
For various reasons not all of these modification orders forwarded by Bristol were not put into practice in Finland. This one described as Bristol Mod 732 "Improved Weather Proofing" dated 29 Dec 1939 applied only to the Bristol Blenheim Mk.IV́s supplied from RAF stocks to the FinnAF during Winter War 1939-40. Corresponding serials were BL-122 - 133.
These airframes received added sealing to the cockpit and gunners station window frames and metal joints. Externally this modification was easily recognized as the gluing on fabric and doping needed one inch overlapping. This resulted in notably "heavier" frames and smaller windows.
These particular airframes are listed in the table. All were produced by Rootes Securities Ltd and some where ex-Blenheim Ís converted into IV́ during manufacture.
L9025 / BL-122
L9027 / BL-123
L9028 / BL-124
L9195 / BL-125
L9196 / BL-126
L9197 / BL-127 Lost over North Sea with all hands (WO Gottschalk, Sgt Kallakari)
L9198 / BL-128
L9199 / BL-129
L9200 / BL-130
L9201 / BL-130
L9202 / BL-131
L9203 / BL-132
Archive information in UK researched by Phil Butler. Airframe ID secured from A.M.Form 78 cards and corresponding FinnAF aircraft & engine files.
Text collected & written by Pentti Manninen, editor of Suomen Ilmailuhistoriallinen Lehti (1994-2019). inscale72production@gmail.com