Started to think about putting new plugs in. They do look well recessed, is there a special tool to get the leads off?

Yes there is, Sealey for one provide one, and there will be offers I'd reckon.

Edit:- using "spark plug lead removal tool" as a search term in eBay and other places should reveal all.

Edited Saturday at 22:454 days by rum4mo

I use this https://it.aliexpress.com/item/1005008359081250.html?spm=a2g0o.productlist.main.1.764duSlYuSlYdb&algo_pvid=79afd053-f1d6-4927-a3d5-eea1f0e81249&algo_exp_id=79afd053-f1d6-4927-a3d5-eea1f0e81249-0&pdp_ext_f=%7B%22order%22%3A%2284%22%2C%22eval%22%3A%221%22%2C%22fromPage%22%3A%22search%22%7D&pdp_npi=6%40dis%21EUR%218.84%218.19%21%21%2167.90%2162.91%21%402103894417804904251428137eb21f%2112000044712196560%21sea%21IT%210%21ABX%211%210%21n_tag%3A-29910%3Bd%3A1c0aa4c6%3Bm03_new_user%3A-29895&curPageLogUid=mBpjNR6n9vuk&utparam-url=scene%3Asearch%7Cquery_from%3A%7Cx_object_id%3A1005008359081250%7C_p_origin_prod%3A

Thick cable ties

Wrap it around

Push it down to the silver part

Pull tight and yank up

Got all 4 of mine off