Compulsory PD day not on my work day

[habibihabibi]

I work 3 days at a school ( secondary specialist) and 2 from home in a unrelated industry. During school holidays I pick up more hours with the non school job but it will never be full time. At school the new and very unpopular Head is saying I must attend PD day on one of the days I am not contracted.
Already I have a timetable full as full can be and more teaching hours than other full timers.
Can I actually be made to come in ?
I have been told I cannot do the day in lieu of a teaching day.

You can't be expected to work any part of a day on which you don't ordinarily work

What's a PD day?

Professional Development Day as far as I am aware.

No you can't. You are contracted for the days you work.

I have, on occasion, attended training days for specific things on my NWDs (say something like Safeguarding which needs to be done), and started from the point of offering the school the choice of either giving me a day off in lieu or to pay me as they would need to pay a supply teacher if I attended training on a working day.
That was possible for me as I could - on the odd occasion - arrange to be available on a NWD. So it depends how useful the PD is for you, and how flexible your other arrangements are.
I found it quite useful, but if it doesn't work for you, you can say no.

I work a pro rata number of training days I'm 0.8 so I do 4 out of 5 training days. This doesn't always work out fairly especially as my nonworking day is Monday.

Different trusts work these out differently. Unfortunately, I think it would be union involvement at this point. I think the most common is to work your normal working days whether or not it is a training or a teaching day.

You have another job so no - they cannot force you. A colleague worked in 2 different schools and had this issue with parents evenings and held firm. School can not expect you to do anything on your non working days.

Do check your directed time - I have a spreadsheet every year to keep a record so it doesn't go over (Im ok with a bit of give and take etc but won't be exploited!)

Email the HT and say: I'd love to take part in the PD on X, but have other work on that day. I would appreciate copies of the relevant handouts and PowerPoints so I can catch up.

Send.

Don't tell them you WFH.

If they say you have to work the training days pro rata, check how many teaching days would be correct pro rata. If most of the training days fall on your non-working day, then you are probably working more than the pro rata number of teaching days. They can't have it both ways...