Glow worm space saver 45-60 cutting out?

My boiler cuts out after 30 seconds cutting off main gas valve so lose main burner and pilot. It had a new t/c a few weeks ago. The pilot will light ok when the main boiler lights it looks ok for 10seconds then pilot flame is jumping around all over the place so the t/c thinks pilot has gone out and cuts off gas. Sometimes it runs for a few days then does the above again. My be coincidence but is mostly windy when happens but first 10 sec seem fine which makes me think it is being starve of oxygen? Flue is clear and fins on heat exchange have been checked and cleaned.