The Doctor

Retro Newbie
Hi all,first time for me so here goes-I have a Holdsworth professional road bike that I’ve owned for over 30 years ,frame no 22573,I checked the number and from what I could tell it is a 1957 model,but when I checked on here it looks like the professional wasn’t made until 1967!!,anyway I’m trying to decide whether to keep or sell but I’ve no idea of value,it looks pretty original apart from seat,is rideable but needs tidying,any ideas??.
The doctor