Thanks, as it's a very interesting question I went back to the HW-database (link once more below), sorted the models and found a heap of information concerning HW77 out of more than 2k entries.
http://www.weihrauch-database.eu/thelist
This first line shows the entry I mentioned in my post above and seems to be incorrect.
683223 HW 77 .22 1977 June 14th 2016 Yes United Kingdom (GB) Greenfields 2016-06-14
These following entries seem to be more accurate and follow more likely your information (so very sad for Mach 1,5
):
To all the bystanders - this does not mean that ser.no. 1 000 094 is the VERY FIRST one put on the market. It's only the first registered HW77 in this compilation. There might very well be even some earlier guns.
1000094 HW 77 .22 1983 1983 No United Kingdom (GB) Trapshot of Lye 2015-07-01
1000330 HW 77 .22 1983 2015 Yes United Kingdom (GB) - 2016-06-05
1000375 HW 77 - 1983 - Yes United Kingdom (GB) - 2014-07-12
1000597 HW 77 .177 1983 2017 Yes Netherlands, The (NL) - 2017-03-28
1001084 HW 77 .22 1983 2017 Yes United Kingdom (GB) - 2017-05-23
1001351 HW 77 .22 1983 1997 Yes United Kingdom (GB) Weybridge Gun Shop 2016-04-12
1001375 HW 77 .22 1983 January 20th 1984 Yes United Kingdom (GB) - 2014-10-29
1003760 HW 77 .22 1984 1985 Yes United Kingdom (GB) - 2014-11-13
1003781 HW 77 .22 1984 January 11th 2016 Yes United Kingdom (GB) - 2016-01-12
1004358 HW 77 - 1984 August 1984 No - - 2014-07-14
1004509 HW 77 .22 1984 2015 Yes United Kingdom (GB) - 2015-12-02
1008828 HW 77 .22 1984 March 22nd 1984 No United Kingdom (GB) - 2015-02-13
1011692 HW 77 .22 1984 March 10th 1990 Yes United Kingdom (GB) T&J McAvoys Standish 2016-12-08
1014920 HW 77 .177 1984 May 30th 2015 Yes United Kingdom (GB) - 2015-05-31